Semiconductor light-emitting device and process for producing the same

ABSTRACT

Semiconductor light-emitting devices are provided. The semiconductor light-emitting devices include a substrate and a crystal layer selectively grown thereon at least a portion of the crystal layer is oriented along a plane that slants to or diagonally intersect a principal plane of orientation associated with the substrate thereby for example, enhancing crystal properties, preventing threading dislocations, and facilitating device miniaturization and separation during manufacturing and use thereof.

RELATED APPLICATION DATA

[0001] The present application is a continuation of InternationalApplication No. PCT/JP01/06212 with an international filing date of Jul.18, 2001. The present application claims priority to Japanese PatentApplication No. P2000-218034 filed on Jul. 18, 2000; Japanese PatentApplication No. P2000-217663 filed on Jul. 18, 2000; Japanese PatentApplication No. P2000-217508 filed on Jul. 18, 2000; Japanese PatentApplication No. P2000-217799 filed on Jul. 18, 2000; Japanese PatentApplication No. P2000-218101 filed on Jul. 18, 2000; and Japanese PatentApplication No. P2001-200183 filed on Jun. 29, 2001. Theabove-referenced Japanese patent applications are incorporated herein byreference to the extent permitted by law.

BACKGROUND OF THE INVENTION

[0002] The present invention generally relates to semiconductor devices.More specifically, the present invention relates to semiconductorlight-emitting devices and processes for producing same.

[0003] Among known semiconductor light-emitting devices is one whichconsists of a low-temperature buffer layer, an n-side contact layer ofSi-doped GaN, an n-side cladding layer of Si-doped GaN, an active layerof Si-doped InGaN, a p-side cladding layer of Mg-doped AlGaN, and ap-side contact layer of Mg-doped GaN, which are sequentially formed ontop of the other over the entire surface of a sapphire substrate.Commercial products of such structure, available in large quantities,are blue and green LEDs (Light-Emitting Diodes) which emit light withwavelengths ranging from 450 nm to 530 nm.

[0004] Growing gallium nitride crystal on a sapphire substrate is acommon practice. The sapphire substrate used for this purpose is usuallyone which has the C-plane (i.e., the (0001) plane in accordance withMiller indices of a hexagonal crystal system) as the principal plane.Consequently, the gallium nitride layer formed on the principal planealso has the C-plane, and the active layer, which is formed parallel tothe principal plane of the substrate, and the cladding layers holdingthe active layer between them are also parallel to the C-plane. Thesemiconductor light-emitting device having crystal layers sequentiallyformed on the basis of the principal plane of the substrate has a smoothsurface desirable for the formation of electrodes, due to the smoothnessof the principal plane of the substrate.

[0005] A disadvantage of growing gallium nitride on a sapphire substrateis that dislocations may densely exist in the crystals due to latticemismatch between them. Attempts have been made to eliminate defects inthe grown crystals by forming a low-temperature buffer layer on thesubstrate. Japanese Patent Laid-open No. Hei 10-312971 discloses thecombination with epitaxial lateral overgrowth (ELO) for reduction incrystal defects.

[0006] Also, Japanese Patent Laid-open No. Hei 10-321910 discloses asemiconductor light-emitting device, wherein the light-generating regionextends vertically to the principal plane of the substrate in ahexagonal prismatic structure which is formed on the substrate such thatits (10-10) or (1-100) M-plane is vertical (i.e., substantiallyperpendicular) to the principal plane of the substrate. The activelayer, vertical to the principal plane of the substrate, is known to beeffective in suppressing defects and dislocations due to latticemismatch with the substrate and reducing strain due to difference in thecoefficient of thermal expansion.

[0007] Moreover, Japanese Patent Laid-open No. Hei 8-255929 discloses aprocess for producing a light-emitting device. The process consists offorming, on a substrate, a layer of gallium nitride compoundsemiconductor of one conductivity type, covering part of the layer witha mask, forming, on the uncovered part, a layer of gallium nitridecompound semiconductor (including a layer of another conductivity type)by selective growth, and forming a p-electrode and an n-electrode.

[0008] The technique of forming a hexagonal prismatic structure verticalto the principal plane of the substrate as disclosed in Japanese PatentLaid-open No. Hei 10-321910 requires that the film obtained by HVPE(hydride vapor phase epitaxy) should be followed by dry etching to givethe (10-10) or (1-100) M-plane. Unfortunately, dry etching inevitablydamages the crystal face. In other words, dry etching deteriorates thecharacteristic properties of crystals despite its effect of suppressingthreading dislocations from the substrate. Further, an additionalproduction step or process stage is required to perform dry etching.

[0009] It is known that selective growth on the C⁺-plane of the sapphiresubstrate gives a crystal layer with sharp peaks surrounded by the(1-101) plane or the S-plane (See Japanese Patent No. 2830814, paragraph0009 of specification). The layer thus obtained is not flat enough forthe electrode to be formed thereon. Therefore, it has never been usedfor electronic devices and light-emitting devices, and is merely used asan underlying layer of crystal structure for further selective growth.

[0010] Any device having a surface parallel to the principal plane ofthe substrate needs a flat surface for good crystal properties. As theresult, it is usually constructed such that the electrodes spreadhorizontally. A disadvantage of this structure is that the horizontallyspread electrodes make for extremely difficult and time-consuming workbecause one must separate miniature chips without cutting thehorizontally spread electrodes. Moreover, the sapphire substrate andnitride (such as GaN) are so hard that they are difficult to cut andrequire a cutting allowance of about 20 μm (i.e., micrometers), therebymaking it even more difficult to cut the miniature chips.

[0011] Additionally, a problem with a light-emitting device in which theprincipal plane of the substrate is a C⁺-plane and the active layer ofgallium nitride is formed parallel to the principal plane of thesubstrate is that there is only one bond from gallium atoms to nitrogenatoms in the C⁺-plane and hence, nitrogen atoms easily dissociate fromthe crystal face of the C⁺-plane, thereby making it difficult for theeffective V/III ratio to be large, which in turn prevents improvement inperformance of crystals constituting the light-emitting device.

[0012] The technology disclosed in Japanese Patent Laid-open No. Hei8-255929 has an advantage of using selective growth which obviates thenecessity of etching, such as reactive ion etching. However, it presentsdifficulties in forming the n-electrode accurately because largeproduction steps occur in its vicinity after the mask layer has beenremoved. A disadvantage of forming the active layer parallel to theprincipal plane of the substrate, as in the light-emitting devicedisclosed in Japanese Patent Laid-open No. Hei 8-255929, is that the endof the active layer is exposed to air, thereby resulting in oxidationand deterioration of the active layer.

[0013] It is known that an LED device can be used as a light source forlarge display (such as projection display). To this end, it is importantfor LED devices to have higher brightness, better reliability, and lowerproduction costs. The brightness of LED devices is governed by twofactors: the internal quantum efficiency, which depends on the crystalproperties of the active layer; and the light emergence efficiency,which is a ratio of light which has escaped from the device to lightwhich has been generated in the device.

[0014] In general, a light-emitting diode has a light-generating region,the typical structure of which is shown in FIG. 1. The major parts ofthe light-generating region include an active layer 400 of, typically,InGaN, a first conductive layer 401 and a second conductive layer 402(which hold the active layer 400 between them), and a reflecting film403 (which also functions as an electrode) on the second conductivelayer 402 opposite to the active layer 400, with the interface betweenthe reflecting film 403 and the second conductive layer 402 functioningas a reflecting plane 404. Part of the light generated by the activelayer 400 emerges directly from the light emerging window 405 in thefirst conductive layer 401, and part of the light advancing toward thesecond conductive layer 402 is reflected by the reflecting plane 404 andthe reflected light advances toward the light emerging window 405 in thefirst conductive layer 401.

[0015] A disadvantage of the above-mentioned light-emitting diode ofordinary structure is that light generated by the active layer 400,however efficient it might be, cannot be extracted from the device dueto total reflection that takes place at an interface between the deviceand the outside, between the device and the transparent substrate,and/or between the transparent substrate and the outside. In otherwords, light incident to the interface at an angle smaller than thecritical angle is subject to total reflection. The critical angledepends on the refractive indices of the two materials forming theinterface. In the light-emitting diode of surface emitting type whichhas the reflecting plane 404 and the light emerging window 405 parallelto each other as shown in FIG. 1, the light which has undergone totalreflection at an angle smaller than the critical angle undergoes totalreflection continuously between the reflecting plane 404 and the lightemerging window 405. Hence, such light cannot be extracted as aneffective output.

[0016] Attempts have been made to improve light emergence efficiency byforming a convex or a slope which changes the optical path in thedevice, so that the convex or slope functions as the reflecting planewhich permits light to emerge efficiently. This technique, however, isnot readily applicable to the GaN semiconductor which is used for blueor green LEDs. At present, it is believed that forming a sophisticatedshape in an extremely small region is not known.

[0017] A sectional view of a light-emitting device of surface emittingtype is shown in section in FIG. 2. It is formed on a substrate forgrowth 500 of sapphire. On the substrate 500 are sequentially formed afirst conductive layer 501 of gallium nitride semiconductor, an activelayer 502 of gallium nitride semiconductor, and a second conductivelayer 503 of gallium nitride semiconductor, all parallel to theprincipal plane of the substrate. The active layer 92 and the secondconductive layer 503 are partly removed such that an opening 506, whosebottom penetrates into the first conductive layer 501, is formed. In theopening 506, a first electrode 504 is formed such that it connects tothe first conductive layer 501. A second electrode 505 is formed on thesecond conductive layer 503, thereby connecting to the second conductivelayer 503.

[0018] A simple way to meet requirements of the light source for largedisplays is to increase the device size according to the desiredbrightness. However, the optical design limits the size of thelight-generating region, which presents difficulties in producing adevice having high brightness as well as a large light-generatingregion. Moreover, the active region in the device is also limited by thearrangement of the light emerging window and the electrodes forefficient current injection. At present, therefore, the requirement forhigh brightness is met by injecting more than the specified current intothe actual device. However, increased current injection impairs devicereliability.

[0019] On the other hand, decreasing the device size of light-emittingdiode is expected to reduce production cost through improvement inyields. There is a strong demand for size reduction in the area whereLEDs in an array having individual pixels for display. However, sizereduction leads to an increased load per unit area, which contradictsthe above-mentioned requirements for high brightness and highreliability.

[0020] Moreover, if the device size is to be reduced below tens ofmicrometers or less, the region for the active layer is greatly limitedby the electrodes 504 and 505 (shown in FIG. 2) and the deviceseparating grooves. The region where the conductive layers 503 and 501come into contact with the electrodes 505 and 504 should be as large aspossible to keep resistance low. However, enlarging the electrodesreduces the area through which light emerges from the active region,which leads to reduced brightness.

[0021] A need, therefore, exists to provide a micro-size light-emittingdevice with efficient light emergence, high brightness, minimum load onthe active layer and controlling threading dislocations from thesubstrate that can be produced under optimal process conditions.

SUMMARY OF THE INVENTION

[0022] The present invention relates to semiconductor light-emittingdevices and methods of producing same. The light-emitting devices of thepresent invention include a crystal structure formed by selective growthand oriented about a crystal plane with respect to a substrate such thatthe light-emitting properties can be enhanced.

[0023] Applicants have discovered that the light-emitting devices of thepresent invention can be produced, for example, under optimal processconditions, such as, without requiring additional production steps orprocess stages, by controlling threading dislocations from the substrateand maintaining desirable crystal properties, thereby also protectingthe active layer from deterioration. In this regard, the light-emittingdevices of the present invention are desirably reliable with minimumload on the active layer (e.g., light-generating region) and can providean enhanced level of brightness due to, for example, the improved lightemergence efficiency.

[0024] To this end, in an embodiment of the present invention, asemiconductor light-emitting device is provided. The semiconductorlight-emitting device includes a substrate including a substrate surfacepositioned along a substrate surface plane, a crystal layer having acrystal surface oriented along a crystal surface plane diagonallyintersecting the substrate surface plane, and a first conductive layer,an active layer, and a second conductive layer each formed along atleast a portion of the crystal surface.

[0025] In an embodiment, the crystal layer is a wurtzite crystalstructure.

[0026] In an embodiment, the crystal layer is composed of a nitridesemiconductor material.

[0027] In an embodiment, the crystal layer is formed by selective growthon the substrate with a material layer capable of growth interposedtherebetween.

[0028] In an embodiment, the material layer capable of growth isselectively removed during selective growth to form the crystal layer.

[0029] In an embodiment, the semiconductor light-emitting device furtherincludes a masking layer having an opening through which the crystallayer is selectively grown.

[0030] In an embodiment, the crystal layer is formed by selective growthsuch that the crystal layer extends laterally from the opening in themasking layer.

[0031] In an embodiment, the substrate plane is a C-plane.

[0032] In an embodiment, the crystal surface plane includes at least oneof a S-plane and a (11-22) plane.

[0033] In an embodiment, the crystal surface plane includes a planehaving a plane orientation inclined at an angle ranging from about 5 toabout 6 degrees with respect to at least one of a S-plane and a (11-22)plane.

[0034] In an embodiment, current is injected into the active layer.

[0035] In an embodiment, active layer includes InGaN.

[0036] In an embodiment, the crystal layer is a substantiallysymmetrical hexagonal structure.

[0037] In an embodiment, a portion of the crystal surface is orientedalong a C-plane and positioned centrally along the crystal structurewith respect to a second portion of the crystal surface that is orientedalong the crystal surface plane which diagonally intersects thesubstrate surface plane.

[0038] In another embodiment according to the present invention, animage display unit is provided. The image display unit includes a numberof semiconductor light-emitting devices arranged so as to emit light inresponse to a signal, each of the semiconductor light-emitting deviceshaving a substrate including a substrate surface positioned along asubstrate surface plane, a crystal layer including a crystal surfaceoriented along a crystal surface plane diagonally intersecting thesubstrate surface plane, and a first conductive layer, an active layer,and a second conductive layer each formed along at least a portion ofthe crystal surface.

[0039] In yet another embodiment according to the present invention, alighting system is provided. The lighting system includes a number ofsemiconductor light-emitting devices, each of the semiconductorlight-emitting devices having a substrate including a substrate surfacepositioned along a substrate surface plane, a crystal layer including acrystal surface oriented along a crystal surface plane diagonallyintersecting the substrate surface plane, and a first conductive layer,an active layer, and a second conductive layer each formed along atleast a portion of the crystal surface.

[0040] In an embodiment, each of the semiconductor light-emittingdevices in the lighting system are arranged so as to emit light inresponse to an identical signal.

[0041] In a further embodiment according to the present invention, aprocess for producing a semiconductor light-emitting device is provided.The process includes the steps of providing a substrate including asubstrate surface oriented along a substrate surface plane, forming acrystal seed layer on the substrate surface, forming a masking layer onthe crystal seed layer, wherein the masking layer includes an opening,forming a crystal layer by selective growth of the crystal seed layerthrough the opening of the masking layer, wherein the crystal layerincludes a crystal layer surface oriented along a crystal layer planethat diagonally intersects the substrate surface, and forming each of afirst conductive layer, an active layer, and a second conductive layeralong at least a portion of the crystal layer surface.

[0042] In an embodiment, the substrate surface plane comprises aC-plane.

[0043] In an embodiment, the process for producing a semiconductorlight-emitting device further includes the step of forming a number ofsemiconductor light-emitting devices spaced apart along the substrate.

[0044] In an embodiment, the process for producing a semiconductorlight-emitting device further includes the step of forming an electrodeon at least a side of each semiconductor light-emitting device.

[0045] According to an embodiment of the present invention, asemiconductor light-emitting device is provided. The semiconductorlight-emitting device includes a substrate including a substrate surfacepositioned along a substrate surface plane, a crystal layer having acrystal layer surface oriented along a crystal surface plane defined asa S-plane which diagonally intersects the substrate surface plane, and alayer of a first conductivity type, an active layer, and a layer of asecond conductivity type each formed along the S-plane.

[0046] In an embodiment, the crystal layer is a wurtzite crystalstructure.

[0047] In an embodiment, the crystal layer is composed of a nitridesemiconductor material.

[0048] In an embodiment, the crystal layer is formed by selective growthon the substrate with a material layer capable of growth interposedtherebetween.

[0049] In an embodiment, the material layer capable of growth isselectively removed during selective growth to form the crystal layer.

[0050] In an embodiment, the semiconductor light-emitting furtherincludes a masking layer having an opening through which the crystallayer is selectively grown.

[0051] In an embodiment, the crystal layer is formed by selective growthsuch that the crystal layer extends laterally from the opening in themasking layer.

[0052] In an embodiment, the substrate surface plane comprises a C+plane.

[0053] In an embodiment, current is injected into the active layer.

[0054] According to yet another embodiment of the present invention, asemiconductor light-emitting device is provided. The semiconductorlight-emitting device includes a substrate including a substrate surfacepositioned along a substrate surface plane, a crystal layer in the shapeof approximately hexagonal pyramid and having a face oriented along anS-plane that diagonally intersects the substrate surface plane, and alayer of a first conductivity type, an active layer, and a layer of asecond conductivity type each formed along at least a portion of theapproximately hexagonal pyramid.

[0055] In an embodiment, current is injected into the active layer suchthat a current density is lower near or at an apex of the approximatelyhexagonal pyramid than in the face of the approximately hexagonalpyramid.

[0056] According to a further embodiment of the present invention, asemiconductor light-emitting device is provided. The semiconductorlight-emitting device includes a substrate including a substrate surfacepositioned along a substrate surface plane, a crystal layer in the shapeof an approximately hexagonal prismoid, having a face oriented about anS-plane, and a top region oriented about a C-plane, and a layer of afirst conductivity type, an active layer, and a layer of a secondconductivity type each formed along at least a portion of theapproximately hexagonal prismoid.

[0057] According to yet another embodiment of the present invention, animage display unit in provided. The image display unit includes a numberof semiconductor light-emitting devices arranged so as to emit light inresponse to a signal, each of the semiconductor light-emitting deviceshaving a substrate including a substrate surface positioned along asubstrate surface plane, a crystal layer having a crystal surfaceoriented along a crystal surface plane defined as a S-plane whichdiagonally intersects the substrate surface plane, and a firstconductive layer, an active layer, and a second conductive layer eachformed along at least a portion of the crystal surface.

[0058] In an embodiment according to the present invention, a lightingsystem is provided. The lighting system includes a number ofsemiconductor light-emitting devices, each of the semiconductorlight-emitting devices having a substrate including a substrate surfacepositioned along a substrate surface plane, a crystal layer having acrystal surface oriented along a crystal surface plane defined as aS-plane which diagonally intersects the substrate surface plane, and afirst conductive layer, an active layer, and a second conductive layereach formed along at least a portion of the crystal surface.

[0059] In an embodiment, each of the semiconductor light-emittingdevices in the lighting system are arranged so as to emit light inresponse to an identical signal.

[0060] In yet another embodiment according to the present invention, aprocess for producing a semiconductor light-emitting device is provided.The process includes the steps providing a substrate including asubstrate surface oriented along a substrate surface plane, forming amasking layer on the substrate, wherein the masking layer includes anopening, forming a crystal layer by selective growth through the openingof the masking layer, wherein the crystal layer includes a crystal layersurface oriented along a crystal layer plane defined as a S-plane whichdiagonally intersects the substrate surface plane, and forming each of afirst conductive layer, an active layer, and a second conductive layeralong at least a portion of the crystal layer surface.

[0061] In an embodiment, the substrate surface plane is a C+ plane.

[0062] In an embodiment, the process for producing a semiconductorlight-emitting device further includes the steps of forming a number ofthe semiconductor light-emitting devices on the substrate, andsubsequently separating the semiconductor light-emitting devices.

[0063] In an embodiment, each separated semiconductor light-emittingdevice has at least one electrode formed on a side.

[0064] In a further embodiment according to the present invention, asemiconductor light-emitting device is provided. The semiconductorlight-emitting device includes a substrate having a substrate surfacepositioned along a substrate surface plane, a crystal grown layer formedby selective growth having a crystal surface oriented along a crystalsurface plane diagonally intersecting the substrate surface plane, anactive layer which is formed along at least a portion of the crystalgrown layer that emits light upon injection of an amount of current, anda reflecting region which is formed substantially parallel to thecrystal surface plane and reflects at least a portion of the lightemerging from the active layer.

[0065] In an embodiment, the active layer is formed from a compoundsemiconductor having a wurtzite crystal structure.

[0066] In an embodiment, the active layer is approximately parallel tothe crystal surface plane.

[0067] In an embodiment, the active layer is approximately parallel to aS-plane.

[0068] In an embodiment, the active layer is approximately parallel to aplane having a plane orientation inclined at an angle ranging from about5 to about 6 degrees with respect to at least one a S-plane and a(11-22) plane.

[0069] In an embodiment, the reflecting region includes at least tworeflecting planes that intersect at an angle less than 180°.

[0070] In an embodiment, the active layer is formed from a nitridecompound semiconductor.

[0071] In an embodiment, the active layer is formed from a galliumnitride compound semiconductor.

[0072] In an embodiment, the active layer contains In.

[0073] In an embodiment, the active layer is separated for each device.

[0074] In an embodiment, the semiconductor light-emitting device furtherincludes an underlying layer formed on the substrate, wherein theselective growth of the crystal grown layer is derived from theunderlying layer.

[0075] According to an embodiment of the present invention. a processfor producing a semiconductor light-emitting device is provided. Theprocess includes the steps of providing a substrate including asubstrate surface oriented along a substrate surface plane, selectivelygrowing a crystal layer having a crystal surface oriented along acrystal surface plane diagonally intersecting the substrate surfaceplane, forming an active layer approximately parallel to the crystalsurface plane, and forming a reflecting region substantially parallel tothe crystal surface plane.

[0076] According to another embodiment of the present invention, asemiconductor light-emitting device is provided. The semiconductorlight-emitting device includes a substrate having a substrate surfaceoriented along a substrate surface plane, a first grown layer having afirst grown layer conductivity type formed on the substrate, a maskinglayer formed on the first grown layer, a second grown layer of a secondgrown layer conductivity type formed by selective growth through anopening in the masking layer having a crystal surface oriented along acrystal surface plane, a first cladding layer including a first claddinglayer conductivity type formed along at least a portion of the crystalsurface plane, an active layer, and a second cladding layer including asecond cladding layer conductivity type, wherein at least one of thefirst cladding layer, the active layer, and the second cladding layercover the masking layer surrounding the opening.

[0077] In an embodiment, the first grown layer conductivity type, thesecond grown layer conductivity type, and the first cladding layerconductivity type are all of a first conductivity type and the secondcladding layer conductivity type is of a second conductivity type.

[0078] In an embodiment, the crystal surface plane of the second grownlayer diagonally intersects the substrate surface plane.

[0079] In an embodiment, the first and second grown layers are composedof a wurtzite crystal structure.

[0080] In an embodiment, the second grown layer is composed of a nitridesemiconductor.

[0081] In an embodiment, the substrate surface plane is a C-plane.

[0082] According to yet another embodiment of the present invention, asemiconductor light-emitting device is provided. The semiconductorlight-emitting device includes a substrate, a first grown layerincluding a first grown layer conductivity type formed on the substrate,a masking layer formed on the first grown layer, a second grown layerincluding a second grown layer conductivity type formed by selectivegrowth through an opening in the masking layer and having a crystalsurface oriented along a crystal surface plane, a first cladding layerincluding a first cladding layer conductivity type formed along at leasta portion of the crystal surface plane, an active layer, and a secondcladding layer including a second cladding layer conductivity type,wherein the first cladding layer, the active layer, and the secondcladding layer are formed as to substantially cover the second grownlayer.

[0083] In an embodiment, the first grown layer conductivity type, thesecond grown layer conductivity type, and the first cladding layerconductivity type are all composed of a first conductivity type whilethe second cladding layer conductivity type is composed of a secondconductivity type.

[0084] According to still another embodiment of the present invention, asemiconductor light-emitting device is provided. The semiconductorlight-emitting device includes a substrate, a first grown layer of afirst grown layer conductivity type formed on the substrate, a maskinglayer formed on the first grown layer, a second grown layer of a secondgrown layer conductivity type formed by selective growth through anopening in the masking layer and including a crystal surface orientedalong a crystal surface plane, a first cladding layer of a firstcladding layer conductivity type formed along at least a portion of thecrystal surface plane, an active layer, and a second cladding layer of asecond cladding layer conductivity type, wherein the first claddinglayer, the active layer, and the second cladding layer are formedsubstantially parallel to the crystal surface plane such that an endregion of at least one of the first cladding layer, the active layer,and the second cladding layer contacts the masking layer.

[0085] In an embodiment, the first grown layer conductivity type, thesecond grown layer conductivity type, and the first cladding layerconductivity type are all of a first conductivity type while the secondcladding layer conductivity type is of a second conductivity type.

[0086] In an embodiment according to the present invention, an imagedisplay unit is provided. The image display unit includes a number ofsemiconductor light-emitting devices arranged so as to emit light inresponse to a signal, each of the semiconductor light-emitting deviceshaving a substrate, a first grown layer of a first conductivity typeformed on the substrate, a masking layer formed on the first grownlayer, a second grown layer of the first conductivity type formed byselective growth through an opening in the masking layer and including acrystal surface oriented along a crystal surface plane, a first claddinglayer of the first conductivity type formed along at least a portion ofthe crystal surface plane, an active layer, and a second cladding layerof a second conductivity type, wherein the first cladding layer, theactive layer, and the second cladding layer are formed substantiallyparallel to the crystal surface plane such that an end region of atleast one of the first cladding layer, the active layer, and the secondcladding layer extends to the masking layer in proximity to the opening.

[0087] In another embodiment according to the present invention, alighting system is provided. The lighting system includes a number ofsemiconductor light-emitting devices, each of the semiconductorlight-emitting devices having a substrate, a first grown layer includinga first conductivity type formed on the substrate, a masking layerformed on the first grown layer, a second grown layer including thefirst conductivity type formed by selective growth through an opening inthe masking layer and including a crystal surface oriented along acrystal surface plane, a first cladding layer including the firstconductivity type formed along at least a portion of the crystal surfaceplane, an active layer, and a second cladding layer of a secondconductivity type, wherein the first cladding layer, the active layer,and the second cladding layer are formed substantially parallel to thecrystal surface plane such that an end region of at least one of thefirst cladding layer, the active layer, and the second cladding layerextends to the masking layer in proximity to the opening.

[0088] In an embodiment, the lighting system is configured such thateach of the semiconductor light-emitting devices are arranged so as toemit light in response to an identical signal.

[0089] According to yet another embodiment of the present invention, aprocess for producing a semiconductor light-emitting device is provided.The process includes the steps of providing a substrate including asubstrate surface oriented along a substrate surface plane, forming afirst grown layer on the substrate, forming a masking layer having anopening on the first grown layer, selectively growing a second grownlayer through the opening in the masking layer, wherein the second grownlayer includes a crystal surface oriented along a crystal surface plane,and forming a cladding layer of a first conductivity type, an activelayer, and a cladding layer of a second conductivity type eachsubstantially parallel to the crystal surface plane extending to themasking layer in proximity to the opening.

[0090] In an embodiment, the crystal surface plane of the second grownlayer diagonally intersects the substrate surface plane.

[0091] According to a further embodiment of the present invention, asemiconductor light-emitting device is provided. The semiconductorlight-emitting device includes a substrate having a substrate surfaceoriented along a substrate surface plane, and an active layer formedalong at least a portion of a selectively grown crystal layer via awindow region along the substrate surface plane such as to be disposedbetween a first conductive layer and a second conductive layer andoriented along an active layer plane that is not parallel to thesubstrate surface plane, and wherein an area of the active layer islarger than at least one of an area of the window region and a projectedarea of the crystal layer derived from projecting the crystal layer tothe substrate surface plane in a normal direction.

[0092] In an embodiment, the active layer is composed of a compoundsemiconductor having a wurtzite crystal structure.

[0093] In an embodiment, the active layer is substantially parallel to aS-plane.

[0094] In an embodiment, the active layer is formed such that it extendslaterally from the window region.

[0095] In an embodiment, the semiconductor light-emitting device furtherincludes a first electrode connected to the first conductive layer, anda second electrode connected to the second conductive layer, wherein thefirst electrode and second electrode are capable of injecting currentinto the active layer.

[0096] In an embodiment, the active layer is a nitride compoundsemiconductor.

[0097] In an embodiment, the active layer is a gallium nitride compoundsemiconductor.

[0098] In an embodiment, the active layer contains In.

[0099] In an embodiment, the semiconductor light-emitting device furtherincludes a number of semiconductor light-emitting devices selectivelygrown such that the active layer of each semiconductor light-emittingdevice is separated from the active layer of adjacent semiconductorlight-emitting devices.

[0100] In an embodiment, the selective growth is derived from anunderlying layer formed on the substrate.

[0101] According to an embodiment of the present invention, asemiconductor light-emitting device is provided. The semiconductorlight-emitting device includes a substrate having a substrate surfaceoriented along a substrate surface plane, and an active layer formed byselective growth such as to be disposed between a first conductive layerand a second conductive layer and oriented along an active layer planethat is not parallel to the substrate surface plane, and wherein aportion of the active layer is directed away from the active layer planetowards the substrate.

[0102] According to yet an embodiment of the present invention, asemiconductor light-emitting device is provided. The semiconductorlight-emitting device includes a substrate including a substrate surfaceoriented along a substrate surface plane, and an active layer formedalong at least a portion of a selectively grown crystal layer such as tobe disposed between a first conductive layer and a second conductivelayer and oriented along an active layer plane that is not parallel tothe substrate surface plane, and wherein an area of the active layergreater than or equal to a sum of a projected area of the crystal layerderived from projecting the crystal layer to the substrate in a normaldirection and an area in which at least one of the conductive layerscontacts a respective electrode formed on the substrate.

[0103] According to a further embodiment of the present invention, aprocess for producing a semiconductor light-emitting device is provided.The process includes the steps of forming an underlying layer on asubstrate, forming a masking layer having a window region on theunderlying layer, selectively growing a crystal grown layer through thewindow region, and forming a first conductive layer, an active layer,and a second conductive layer on a surface of the crystal grown layer,wherein the active layer includes a crystal surface with a surface arealarger than a projected area derived from projecting the crystal surfacetoward the substrate in a normal direction.

[0104] According to another embodiment of the present invention, aprocess for producing a semiconductor light-emitting device is provided.The process includes the steps of providing a first substrate includinga first substrate surface oriented along a first substrate surfaceplane, forming a crystal seed layer on the first substrate surface,forming a masking layer on the crystal seed layer, wherein the maskinglayer includes an opening, forming a crystal layer by selective growthof the crystal seed layer through the opening of the masking layer,wherein the crystal layer includes a crystal layer surface orientedalong a crystal layer plane that diagonally intersects the firstsubstrate surface plane, forming each of a first conductive layer, anactive layer, and a second conductive layer along at least a portion ofthe crystal layer surface, embedding each of the first conductive layer,the active layer and the second conductive layer and the secondconductive layer in a resin material layer formed on a second substrate,removing the second substrate by laser abrasion, separating the crystalseed layer and masking layer from a substrate region of the substrate,and forming an electrode on at least a portion of the substrate region.

[0105] In an embodiment, the crystal seed layer and the masking layerare separated by peeling off.

[0106] Additional features and advantages of the present invention aredescribed in, and will be apparent from, the following DetailedDescription of the Invention and the Figures.

BRIEF DESCRIPTION OF THE FIGURES

[0107]FIG. 1 is a sectional view showing a structure of a semiconductorlight-emitting device.

[0108]FIG. 2 is a sectional view showing another structure of asemiconductor light-emitting device.

[0109]FIGS. 3A and 3B are diagrams showing the step of forming a mask inthe production of the semiconductor light-emitting device in Example 1of an embodiment of the present invention, wherein FIG. 3A is asectional view and FIG. 3B is a perspective view.

[0110]FIGS. 4A and 4B are diagrams showing the step of forming asilicon-doped GaN layer in the production of the semiconductorlight-emitting device in Example 1 of an embodiment of the presentinvention, wherein FIG. 4A is a sectional view and FIG. 4B is aperspective view.

[0111]FIGS. 5A and 5B are diagrams showing the step of forming a windowfor crystal growth in the production of the semiconductor light-emittingdevice in Example 1 of an embodiment of the present invention, whereinFIG. 5A is a sectional view and FIG. 5B is a perspective view.

[0112]FIGS. 6A and 6B are diagrams showing the step of forming an activelayer etc. in the production of the semiconductor light-emitting devicein Example 1 of an embodiment of the present invention, wherein FIG. 6Ais a sectional view and FIG. 6B is a perspective view.

[0113]FIGS. 7A and 7B are diagrams showing the step of forming anelectrode in the production of the semiconductor light-emitting devicein Example 1 of an embodiment of the present invention, wherein FIG. 7Ais a sectional view and FIG. 7B is a perspective view.

[0114]FIGS. 8A and 8B are diagrams showing the step of separatingdevices in the production of the semiconductor light-emitting device inExample 1 of an embodiment of the present invention, wherein FIG. 8A isa sectional view and FIG. 8B is a perspective view.

[0115]FIG. 9 is a sectional view showing the structure of thesemiconductor light-emitting device in Example 1 of an embodiment of thepresent invention.

[0116]FIGS. 10A and 10B are diagrams showing the step of forming a maskin the production of the semiconductor light-emitting device in Example2 of an embodiment of the present invention, wherein FIG. 10A is asectional view and FIG. 10B is a perspective view.

[0117]FIGS. 11A and 11B are diagrams showing the step of selectiveremoval in the production of the semiconductor light-emitting device inExample 2 of an embodiment of the present invention, wherein FIG. 11A isa sectional view and FIG. 11B is a perspective view.

[0118]FIGS. 12A and 12B are diagrams showing the step of forming acrystal layer in the production of the semiconductor light-emittingdevice in Example 2 of an embodiment of the present invention, whereinFIG. 12A is a sectional view and FIG. 12B is a perspective view.

[0119]FIGS. 13A and 13B are diagrams showing the step of forming anactive layer in the production of the semiconductor light-emittingdevice in Example 2 of an embodiment of the present invention, whereinFIG. 13A is a sectional view and FIG. 13B is a perspective view.

[0120]FIGS. 14A and 14B are diagrams showing the step of forming anelectrode in the production of the semiconductor light-emitting devicein Example 2 of an embodiment of the present invention, wherein FIG. 14Ais a sectional view and FIG. 14B is a perspective view.

[0121]FIGS. 15A and 15B are diagrams showing the step of separatingdevices in the production of the semiconductor light-emitting device inExample 2 of an embodiment of the present invention, wherein FIG. 15A isa sectional view and FIG. 15B is a perspective view.

[0122]FIG. 16 is a sectional view showing the semiconductorlight-emitting device in Example 2 of an embodiment of the presentinvention.

[0123]FIGS. 17A and 17B are diagrams showing the step of separatingdevices in a modified way in the production of the semiconductorlight-emitting device in Example 2 of an embodiment of the presentinvention, wherein FIG. 17A is a sectional view and FIG. 17B is aperspective view.

[0124]FIGS. 18A and 18B are diagrams showing the step of forming a maskin the production of the semiconductor light-emitting device in Example3 of an embodiment of the present invention, wherein FIG. 18A is asectional view and FIG. 18B is a perspective view.

[0125]FIGS. 19A and 19B are diagrams showing the step of forming acrystal layer in the production of the semiconductor light-emittingdevice in Example 3 of an embodiment of the present invention, whereinFIG. 19A is a sectional view and FIG. 19B is a perspective view.

[0126]FIGS. 20A and 20B are diagrams showing the step of forming anactive layer in the production of the semiconductor light-emittingdevice in Example 3 of an embodiment of the present invention, whereinFIG. 20A is a sectional view and FIG. 20B is a perspective view.

[0127]FIGS. 21A and 21B are diagrams showing the step of forming anelectrode in the production of the semiconductor light-emitting devicein Example 3 of an embodiment of the present invention, wherein FIG. 21Ais a sectional view and FIG. 21B is a perspective view.

[0128]FIGS. 22A and 22B are diagrams showing the step of separatingdevices in the production of the semiconductor light-emitting device inExample 3 of an embodiment of the present invention, wherein FIG. 22A isa sectional view and FIG. 22B is a perspective view.

[0129]FIG. 23 is a sectional view showing the semiconductorlight-emitting device in Example 3 of an embodiment of the presentinvention.

[0130]FIGS. 24A and 24B are diagrams showing the step of forming a maskin the production of the semiconductor light-emitting device in Example4 of an embodiment of the present invention, wherein FIG. 24A is asectional view and FIG. 24B is a perspective view.

[0131]FIGS. 25A and 25B are diagrams showing the step of forming acrystal layer in the production of the semiconductor light-emittingdevice in Example 4 of an embodiment of the present invention, whereinFIG. 25A is a sectional view and FIG. 25B is a perspective view.

[0132]FIGS. 26A and 26B are diagrams showing the step of forming anactive layer in the production of the semiconductor light-emittingdevice in Example 4 of an embodiment of the present invention, whereinFIG. 26A is a sectional view and FIG. 26B is a perspective view.

[0133]FIGS. 27A and 27B are diagrams showing the step of forming anelectrode in the production of the semiconductor light-emitting devicein Example 4 of an embodiment of the present invention, wherein FIG. 27Ais a sectional view and FIG. 27B is a perspective view.

[0134]FIGS. 28A and 28B are diagrams showing the step of separatingdevices in the production of the semiconductor light-emitting device inExample 4 of an embodiment of the present invention, wherein FIG. 28A isa sectional view and FIG. 28B is a perspective view.

[0135]FIG. 29 is a sectional view showing the semiconductorlight-emitting device in Example 4 of an embodiment of the presentinvention.

[0136]FIGS. 30A and 30B are diagrams showing the step of forming anelectrode in the production of the semiconductor light-emitting devicein Example 5 of an embodiment of the present invention, wherein FIG. 30Ais a sectional view and FIG. 30B is a perspective view.

[0137]FIGS. 31A and 31B are diagrams showing the step of separatingdevices in the production of the semiconductor light-emitting device inExample 5 of an embodiment of the present invention, wherein FIG. 31A isa sectional view and FIG. 31B is a perspective view.

[0138]FIG. 32 is a sectional view showing the semiconductorlight-emitting device in Example 5 of an embodiment of the presentinvention.

[0139]FIGS. 33A and 33B are diagrams showing the step of forming ap-electrode in the production of the semiconductor light-emitting devicein Example 6 of an embodiment of the present invention, wherein FIG. 33Ais a sectional view and FIG. 33B is a perspective view.

[0140]FIGS. 34A and 34B are diagrams showing the step of separatingdevices in the production of the semiconductor light-emitting device inExample 6 of an embodiment of the present invention, wherein FIG. 34A isa sectional view and FIG. 34B is a perspective view.

[0141]FIGS. 35A and 35B are diagrams showing the step of forming ann-electrode in the production of the semiconductor light-emitting devicein Example 6 of an embodiment of the present invention, wherein FIG. 35Ais a sectional view and FIG. 35B is a perspective view.

[0142]FIGS. 36A, 36B and 36C are diagrams showing the step of forming ann-electrode in a modified way according to an embodiment of the presentinvention, wherein FIG. 36A is a schematic sectional view showing thelaser abrasion step, FIG. 36B is a schematic sectional view showing theRIE step, and FIG. 36C is a schematic sectional view showing the step offorming an n-electrode.

[0143]FIG. 37 is a sectional view showing the semiconductorlight-emitting device in Example 6 of an embodiment of the presentinvention.

[0144]FIG. 38 is a rear perspective view showing another structure ofthe semiconductor light-emitting device in Example 6 of an embodiment ofthe present invention.

[0145]FIGS. 39A and 39B are diagrams showing the step of forming atransparent electrode in the production of the modified semiconductorlight-emitting device in Example 6 of an embodiment of the presentinvention, wherein FIG. 39A is a sectional view and FIG. 39B is aperspective view.

[0146]FIG. 40 is a sectional view showing the modified semiconductorlight-emitting device in Example 6 of an embodiment of the presentinvention.

[0147]FIG. 41 is a perspective view showing the step of forming a maskin the production of the semiconductor light-emitting device in Example7 of an embodiment of the present invention.

[0148]FIG. 42 is a perspective view showing the step of forming anactive layer in the production of the semiconductor light-emittingdevice in Example 7 of an embodiment of the present invention.

[0149]FIG. 43 is a perspective view showing the step of forming anelectrode in the production of the modified semiconductor light-emittingdevice in Example 7 of an embodiment of the present invention.

[0150]FIG. 44 is a sectional view showing the semiconductorlight-emitting device in Example 7 of an embodiment of the presentinvention.

[0151]FIGS. 45A and 45B are diagrams showing the step of forming a maskin the production of the semiconductor light-emitting device in Example8 of an embodiment of the present invention, wherein FIG. 45A is asectional view and FIG. 45B is a perspective view.

[0152]FIGS. 46A and 46B are diagrams showing the step of forming acrystal layer in the production of the semiconductor light-emittingdevice in Example 8 of an embodiment of the present invention, whereinFIG. 46A is a sectional view and FIG. 46B is a perspective view.

[0153]FIGS. 47A and 47B are diagrams showing the step of forming anactive layer in the production of the semiconductor light-emittingdevice in Example 8 of an embodiment of the present invention, whereinFIG. 47A is a sectional view and FIG. 47B is a perspective view.

[0154]FIGS. 48A and 48B are diagrams showing the step of forming anelectrode in the production of the semiconductor light-emitting devicein Example 8 of an embodiment of the present invention, wherein FIG. 48Ais a sectional view and FIG. 48B is a perspective view.

[0155]FIGS. 49A and 49B are diagrams showing the step of separatingdevices in the production of the semiconductor light-emitting device inExample 8 of an embodiment of the present invention, wherein FIG. 49A isa sectional view and FIG. 49B is a perspective view.

[0156]FIG. 50 is a sectional view showing the semiconductorlight-emitting device in Example 8 of an embodiment of the presentinvention.

[0157]FIGS. 51A and 51B are diagrams showing the step of forming anelectrode in the production of the modified semiconductor light-emittingdevice in Example 8 of an embodiment of the present invention, whereinFIG. 51A is a sectional view and FIG. 51B is a perspective view.

[0158]FIG. 52 is a sectional view showing the modified semiconductorlight-emitting device in Example 8 of an embodiment of the presentinvention.

[0159]FIGS. 53A and 53B are diagrams showing the step of forming anelectrode in the production of the semiconductor light-emitting devicein Example 9 of an embodiment of the present invention, wherein FIG. 53Ais a sectional view and FIG. 53B is a perspective view.

[0160]FIG. 54 is a partial perspective view showing an apparatus thatutilizes the semiconductor light-emitting device in Example 10 of anembodiment of the present invention.

[0161]FIG. 55 is a sectional view showing the structure of thesemiconductor light-emitting device in Example 11 of an embodiment ofthe present invention.

[0162]FIG. 56 is a sectional view illustrating the area W1 of the windowregion of the semiconductor light-emitting device in Example 11 of anembodiment of the present invention.

[0163]FIG. 57 is a sectional view illustrating the projected area W2 ofthe crystal grown layer of the semiconductor light-emitting device inExample 11 of an embodiment of the present invention.

[0164]FIG. 58 is a perspective view showing the structure of thesemiconductor light-emitting device in Example 12 of an embodiment ofthe present invention that is characterized by the crystal grown layerwhich is formed in a stripe pattern.

[0165]FIG. 59 is a perspective view showing the structure of thesemiconductor light-emitting device in Example 13 of an embodiment ofthe present invention that is characterized by the crystal grown layerwhich is formed in a pattern of elongated quadrangular prismoids.

[0166]FIG. 60 is a perspective view showing the structure of thesemiconductor light-emitting device in Example 14 of an embodiment ofthe present invention that is characterized by the crystal grown layerwhich is formed in a pattern of quadrangular prismoids.

[0167]FIG. 61 is a perspective view showing the structure of thesemiconductor light-emitting device Example 15 of an embodiment of thepresent invention that is characterized by the crystal grown layer whichis formed in a pattern of hexagonal pyramids.

[0168]FIG. 62 is a perspective view showing the structure of thesemiconductor light-emitting device Example 16 of an embodiment of thepresent invention that is characterized by the crystal grown layer whichis formed in a pattern of hexagonal prismoids.

[0169]FIG. 63 is a perspective view showing the step of forming anunderlying layer for growth in the production of the semiconductorlight-emitting device in Example 17 of an embodiment of the presentinvention.

[0170]FIG. 64 is a perspective view showing the step of forming windowregions in the production of the semiconductor light-emitting device inExample 17 of an embodiment of the present invention.

[0171]FIG. 65 is a perspective view showing the step of forming acrystal grown layer in the production of the semiconductorlight-emitting device in Example 17 of an embodiment of the presentinvention.

[0172]FIG. 66 is a perspective view showing the step of forming a layerof a second conductivity type in the production of the semiconductorlight-emitting device in Example 17 of an embodiment of the presentinvention.

[0173]FIG. 67 is a perspective view showing the step of forming acontact region in the production of the semiconductor light-emittingdevice in Example 17 of an embodiment of the present invention.

[0174]FIG. 68 is a perspective view showing the step of forming anelectrode in the production of the semiconductor light-emitting devicein Example 17 of an embodiment of the present invention.

[0175]FIG. 69 is a sectional view showing the semiconductorlight-emitting device in Example 18 of an embodiment of the presentinvention.

[0176]FIG. 70 is a sectional view showing the structure of thesemiconductor light-emitting device in Example 19 of an embodiment ofthe present invention.

[0177]FIG. 71 is a sectional view showing a portion of the semiconductorlight-emitting device in Example 19 of an embodiment of the presentinvention.

[0178]FIG. 72 is a perspective view showing the model of crystal grownlayer that is used as the basis for calculations in production of thesemiconductor light-emitting device in the Examples of an embodiment ofthe present invention.

[0179]FIG. 73 is a schematic diagram showing the model which is used forcalculations of angle dependence in production of the semiconductorlight-emitting device in Examples of an embodiment of the presentinvention.

[0180]FIG. 74 is a line graph showing the angle dependence on the lightemergence efficiency which is obtained from the above-mentionedcalculations in accordance with an embodiment of the present invention.

[0181]FIG. 75 is a schematic diagram showing the model which is used forcalculations of height dependence in production of the semiconductorlight-emitting device in Examples of an embodiment of the presentinvention.

[0182]FIG. 76 is a line graph showing the height dependence on the lightemergence efficiency which is obtained from the above-mentionedcalculations in accordance with an embodiment of the present invention.

[0183]FIG. 77 is a perspective view showing the structure of thesemiconductor light-emitting device in Example 20 of the presentinvention that is characterized by the crystal grown layer which isformed in a stripe pattern in accordance with an embodiment of thepresent invention.

[0184]FIG. 78 is a perspective view showing the structure of thesemiconductor light-emitting device in Example 21 of an embodiment ofthe present invention that is characterized by the crystal grown layerwhich is formed in a pattern of elongated quadrangular prismoids.

[0185]FIG. 79 is a perspective view showing the structure of thesemiconductor light-emitting device in Example 22 of an embodiment ofthe present invention that is characterized by the crystal grown layerwhich is formed in a pattern of quadrangular prismoids.

[0186]FIG. 80 is a perspective view showing the structure of thesemiconductor light-emitting device Example 23 of an embodiment of thepresent invention that is characterized by the crystal grown layer whichis formed in a pattern of hexagonal pyramids.

[0187]FIG. 81 is a perspective view showing the structure of thesemiconductor light-emitting device Example 24 of an embodiment of thepresent invention that is characterized by the crystal grown layer whichis formed in a pattern of hexagonal prismoids.

[0188]FIG. 82 is a perspective view showing the structure of thesemiconductor light-emitting device Example 25 of an embodiment of thepresent invention that is characterized by the crystal grown layer whichis formed in a mixed pattern of hexagonal pyramids and quadrangularprismoids.

[0189]FIG. 83 is a perspective view showing the step of forming anunderlying layer for growth in the production of the semiconductorlight-emitting device in Example 25 of an embodiment of the presentinvention.

[0190]FIG. 84 is a perspective view showing the step of forming windowregions in the production of the semiconductor light-emitting device inExample 25 of an embodiment of the present invention.

[0191]FIG. 85 is a perspective view showing the step of forming acrystal grown layer in the production of the semiconductorlight-emitting device in Example 25 of an embodiment of the presentinvention.

[0192]FIG. 86 is a perspective view showing the step of forming a layerof a second conductivity type in the production of the semiconductorlight-emitting device in Example 25 of an embodiment of the presentinvention.

[0193]FIG. 87 is a perspective view showing the step of forming acontact region in the production of the semiconductor light-emittingdevice in Example 25 of an embodiment of the present invention.

[0194]FIG. 88 is a perspective view showing the step of forming anelectrode in the production of the semiconductor light-emitting devicein Example 25 of an embodiment of the present invention.

[0195]FIG. 89 is a sectional view showing the semiconductorlight-emitting device in Example 26 of an embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE INVENTION

[0196] A semiconductor light-emitting device according to an embodimentof the present invention includes a substrate and a crystal layer formedthereon, the crystal layer having a slant crystal plane slanting to(i.e., diagonally intersecting) the principal plane of the substrate,and further includes a layer of a first conductivity type, an activelayer, and a layer of a second conductivity type which are formedparallel to the slant crystal plane on the crystal layer.

[0197] The substrate used in an embodiment of the present invention isnot specifically restricted so long as it forms a crystal layer having aslant crystal plane slanting to the principal plane of the substrate.Various substrates are available including, for example, sapphire(Al₂O₃, having A-plane, R-plane, or C-plane), SiC (including 6H, 4H, and3C), GaN, Si, ZnS, ZnO, AlN, LiMgO, GaAs, MgAl₂O₄, and InAlGaN. Of theabove-described substrates, hexagonal or cubic crystal based substratesare preferred, with the hexagonal substrates being most preferred. Asapphire substrate whose principal plane is the C-plane can be used. Ingeneral, the C-plane is a plane on which a gallium nitride (GaN) basedcompound for a semiconductor is usually grown, and the C-plane as theprincipal plane of the substrate may have a plane orientation which isinclined at an angle of 5 or 6 degrees.

[0198] In an embodiment, the substrate itself is not a constituent ofthe light-emitting device and is used merely to hold device parts and isremoved before the device is completed.

[0199] In an embodiment, the crystal layer formed on the substrate has aslant crystal plane slanting to the principal plane of the substrate.This crystal layer is not specifically restricted so long as it permitsthe light-generating region (mentioned later) to be formed thereon,which consists of a layer of a first conductivity type, an active layer,and a layer of a second conductivity type, and is parallel to the slantcrystal plane slanting to the principal plane of the substrate. Amaterial of a wurtzite crystal structure is desirable for the crystallayer. However, it should be appreciated that a variety of suitablecrystal structures can be utilized.

[0200] The crystal layer can be formed of a variety of different andsuitable materials. In an embodiment, the crystal layer may be formedfrom a group III based compound semiconductor, a BeMgZnCdS basedcompound semiconductor, a BeMgZnCdO based compound semiconductor, agallium nitride (GaN) based compound semiconductor, an aluminum nitride(AlN) based compound semiconductor, an indium nitride (InN) basedcompound semiconductor, an indium gallium nitride (InGaN) based compoundsemiconductor, an alum aluminum gallium nitride (AlGaN) based compoundsemiconductor, the like and combinations thereof. In an embodiment,Nitride semiconductors such as a gallium nitride based compoundsemiconductor are preferred.

[0201] It should be noted that in the present invention, InGaN, AlGaN,GaN, and the like do not necessarily imply nitride semiconductors ofternary or binary mixed crystals alone. InGaN, for example, may containa trace amount of Al and other impurities which do not affect thefunction of InGaN. Such compound semiconductors are within the scope ofthe present invention.

[0202] The crystal layer can be grown by chemical vapor deposition ofvarious kinds, such as metal organic chemical vapor deposition (MOCVD)including, for example, metal organic vapor phase epitaxy (MOVPE),molecular beam epitaxy (MBE), hydride vapor phase epitaxy (HVPE), andthe like. In an embodiment, MOCVD is preferred because it rapidly yieldsa crystal layer with desirable crystal properties. The MOCVD methodcommonly employs alkyl metal compounds, such as TMG (trimethylgallium)or TEG (triethylgallium) as a Ga source, TMA (trimethylaluminum) or TEA(triethylaluminum) as an Al source, and TMI (trimethylindium) or TEI(triethylindium) as an In source. It also employs ammonia gas orhydrazine gas as a nitrogen source, and other gases as an impuritysource, for example, silane gas for Si, germane gas for Ge, Cp₂Mg(cyclopentadienylmagnesium) for Mg, and DEZ (diethylzinc) for Zn. Ingeneral, MOCVD is carried out by feeding the gases to the surface of thesubstrate which is heated at about 600° C. or above, so that the gasesdecompose to give an InAlGaN based compound semiconductor by epitaxialgrowth.

[0203] It is desirable, in an embodiment, that the crystal layer beformed after an underlying layer for growth has been formed on thesubstrate. In an embodiment, the underlying layer for growth may be agallium nitride layer, an aluminum nitride layer, or the like. It mayalso be a combination of a low-temperature buffer layer and ahigh-temperature buffer layer, or a combination of a buffer layer and acrystal seed layer (functioning as a crystal seed). As in the crystallayer, the underlying layer for growth can also be formed by chemicalvapor deposition such as metal organic chemical vapor deposition(MOCVD), molecular beam epitaxy (MBE), hydride vapor phase epitaxy(HVPE), and the like. Growing the crystal layer from the low-temperaturebuffer layer causes a problem that polycrystals are likely toprecipitate on the mask. This problem is overcome by forming a crystalseed layer and then growing thereon a plane differing from thesubstrate. Thus, it is possible to grow crystals having desirablecrystal properties. In the case of selective growth for crystal growing,it is necessary to grow crystals from the buffer layer if there existsno crystal seed layer. Selective growth from the buffer layer causescrystals to grow from the part where the crystal growth is not required.Consequently, the crystal seed layer permits crystals to growselectively in the region where crystal growth is necessary. The bufferlayer is intended to relieve lattice mismatch between the substrate andthe nitride semiconductor. Therefore, there may be an instance where thebuffer layer is not formed if the substrate has a lattice constant closeto that of the nitride semiconductor. For example, there may be aninstance where an AlN buffer layer is formed on SiC without loweringtemperature or an AlN or GaN buffer layer is formed on a Si substratewithout lowering temperature. Thus, it is also possible to form GaN ofgood quality. The structure without any buffer layer is acceptable ifthe substrate is GaN or a suitable material.

[0204] According to an embodiment of the present invention, selectivegrowth can be used to form the slant crystal plane slanting to theprincipal plane of the substrate. The slant crystal plane slanting tothe principal plane of the substrate depends on the principal plane ofthe substrate used. It is selected from such crystal planes as the(1-100) plane [M-plane], the (1-101) plane [S-plane], the (11-20) plane[A-plane], the (1-102) plane [R-plane], the (11-23) plane [N-plane], the(11-22) plane, the like and combinations thereof when the principalplane of the substrate is the (0001) plane [C-plane] of a wurtzitestructure.

[0205] It is noted that the plane terminology (e.g., S-plane, C-plane orthe like) as used herein denotes crystal planes in accordance withMiller indices of a hexagonal crystal system. Where appropriate,throughout the specification, these planes are intended to include morethan one plane in the hexagonal crystal system. For example, the S-planeis listed above as corresponding to the (1-101) plane, but it should beunderstood that, where appropriate, the S-plane is intended to includeone or more of the planes relating to the family of planes making up acrystal structure having the S-plane. For example, if the crystalstructure being described is a hexagonal pyramid having the S-plane,planes corresponding to each side face of the hexagonal pyramid would beincluded in the family of planes denoted by the S-plane. For example, inaddition to the (1-101) plane, a hexagonal pyramid has side facescorresponding to the (10-11), (01-11), (-1101) and (0-111) planes.

[0206] In an embodiment, the S-plane and the (11-22) plane arepreferred. Naturally, equivalent crystal planes may also be used, forexample, planes having a plane orientation inclined at an angle of about5 to about 6 degrees to the S-plane or the (11-22) plane. In particular,the S-plane is a stable plane which is obtained when selective growth iscarried out on the C⁺-plane. The S-plane can be obtained comparativelyeasily, and it is expressed as a (1-101) plane in accordance with Millerindices of a hexagonal crystal system. Just as the C-plane includes theC⁺-plane and the C⁻-plane, the S-plane includes the S⁺-plane and theS⁻-plane. In this specification, the S⁺-plane is grown on the C⁺-planeGaN and it is referred to as the S-plane unless otherwise stated.Additionally, of the S-planes, the S⁺-plane is stable.

[0207] The index of the C⁺-plane is (0001). In the case where thecrystal layer is formed from a gallium nitride based compoundsemiconductor (as mentioned above), the number of bonds from Ga to N is2 or 3 on the S-plane. This number is second to that on the C-plane.Since the C⁻-plane cannot be obtained on the C⁺-plane in practice, thenumber of bonds on the S-plane is the largest. For example, when anitride is grown on a sapphire substrate having the C-plane as theprincipal plane, the nitride of wurtzite structure has a surface ofC⁺-plane. However, it is possible to form the S-plane if selectivegrowth is employed. On the plane parallel to the C-plane, the bond of N(which easily releases itself) combines with one bond of Ga, whereas onthe slant S-plane, it combines with at least one bond. This causes theeffective V/III ratio to increase, thereby improving the crystalproperties of the laminate structure. In addition, growth in thedirection different from the orientation of the substrate bendsdislocations extending from the substrate, thereby favorably decreasingdefects.

[0208] In a semiconductor light-emitting device according to anembodiment of the present invention, the crystal layer has a slantcrystal plane slanting to the principal plane of the substrate. Thecrystal layer may be formed such that the S-plane (or any other planesubstantially equivalent thereto) constitutes the side faces of anapproximately hexagonal pyramid, or the S-plane (or any other planesubstantially equivalent thereto) constitutes the side faces of anapproximately hexagonal prismoid and the C-plane (or any other planesubstantially equivalent thereto) constitutes the top plane of theapproximately hexagonal prismoid. The approximately hexagonal pyramidand approximately hexagonal prismoid do not necessarily need to beexactly hexagonal. They may include those which have one or more missingfaces. In a preferred embodiment, the slant crystal plane is hexagonaland is arranged approximately symmetrical. The term “approximatelysymmetrical,” as used herein, embraces completely symmetrical andslightly asymmetrical. The edge between the crystal planes of thecrystal layer does not necessarily need to be straight. Also, theapproximately hexagonal pyramid or approximately hexagonal prismoid maybe in an elongated shape.

[0209] In actuality, selective growth is accomplished in an embodimentby using a selectively removed part of the underlying layer for growthor by using a selectively made opening in the masking layer on theunderlying layer for growth or in the masking layer which is formedbefore the underlying layer for growth has been formed. For example,when the underlying layer for growth consists of a buffer layer and acrystal seed layer, the crystal seed layer on the buffer layer isdivided into scattered small regions, each about 10 μm in diameter.Crystals are grown from these small regions such that the crystal layerhaving the S-plane is formed. For example, the finely divided crystalseed layers may be arranged apart from one another, thereby allowingfinished light-emitting devices to be separated. Individual smallregions may take on any shape such as a stripe, a lattice, a circle, asquare, a hexagon, a triangle, a rectangle, a rhombus, the like andcombinations thereof. Selective growth may also be accomplished byforming a masking layer on the underlying layer for growth andselectively forming openings (i.e., window regions) in the maskinglayer. In an embodiment, the masking layer may be a silicon oxide layer,a silicon nitride layer, or the like. The approximately hexagonalpyramids or prismoids in an elongated shape (as mentioned above) may beformed if the window region in the masking layer or the crystal seedlayer is formed in an elongated shape.

[0210] In an embodiment, if the window region in the masking layer forselective growth is a circle of about 10 μm in diameter (or a hexagonwhose one side coincides with the (1-100) direction or (11-20)direction), it is possible to easily form a selectively grown regionwhich is about twice as large as the window region. Also, the S-plane ina direction different from the substrate produces the effect of bendingor isolating dislocations. This contributes to reduction in the densityof dislocations.

[0211] Observation by cathode luminescence on the grown hexagonalprismoid indicates that the S-plane has desirable crystal properties andis superior to the C⁺-plane in light emission efficiency. Growing theInGaN active layer at about 700° C. to about 800° C. makes ammoniadecompose slowly and hence, requires more nitrogen species. Observationswith an AFM revealed that the surface has regular steps suitable forInGaN uptake. It was also found that the Mg-doped layer, whose grownsurface observed by AFM is usually in poor state, improves owing to theS-plane and that the doping condition is considerably different.Observation by microscopic photoluminescence mapping (which has aresolving power of about 0.5 μm to about 1 μm) revealed that the S-planeformed by selective growth is uniform. The S-plane formed on theC⁺-plane by the ordinary process has irregularities at a pitch of about1 μm. Also, observation with an SEM revealed that the side face issmoother than the C⁺-plane.

[0212] If selective growth is carried out, using a mask, such thatcrystals grow only over the opening of the mask, crystals do not grow inthe lateral direction. Thus, it is possible to employ microchannelepitaxy to make crystals to grow in the lateral direction, extendingbeyond the window region. It is known that growing in the lateraldirection by microchannel epitaxy readily avoids threading dislocationsand hence, reduces dislocations. Thus, growing in the lateral directiongives an enlarged light-generating region and contributes to uniformcurrent flow and reduced current density.

[0213] A semiconductor light-emitting device according to an embodimentof the present invention includes a substrate and a crystal layer formedthereon, the crystal layer having a slant crystal plane slanting to theprincipal plane of the substrate, and further includes a layer of afirst conductivity type, an active layer, and a layer of a secondconductivity type which are formed parallel to the slant crystal planeon the crystal layer. The layer of a first conductivity type is acladding layer of p-type or n-type, and the layer of a secondconductivity type is a cladding layer of an opposite type. For example,if the crystal layer constituting the S-plane is formed from asilicon-doped gallium nitride based compound semiconductor layer, ann-type cladding layer is formed from a silicon-doped gallium nitridecompound semiconductor. On this cladding layer, an active layer of InGaNis formed. On this active layer, a p-type cladding layer ofmagnesium-doped gallium nitride based compound semiconductor is formed.Thus, the desired double heterojunction structure is obtained. Anotherpossible structure is such that the active layer of InGaN is heldbetween two AlGaN layers. The active layer may be of a single bulk layerstructure. Alternatively, it may be of single quantum well (SQW)structure, double quantum well (DQW) structure, or multiple quantum well(MQW) structure. The quantum well structure may use a barrier layer forseparation of quantum wells, if necessary. The light-emitting devicehaving an active layer of InGaN is easy to produce and has desirablelight emission characteristics. Moreover, the InGaN layer readilycrystallizes and has desirable crystal properties on the S-plane fromwhich nitrogen atoms hardly release themselves, thereby increasing thelight emission efficiency.

[0214] Additionally, a nitride compound semiconductor tends to becomen-type due to nitrogen holes which occur in crystal even though it isnot doped. However, it can be deliberately made n-type, having a desiredcarrier density, if it is doped with an ordinary donor impurity (such asSi, Ge, and Se) during crystal growth. Also, a nitride semiconductor canbe made p-type by doping with an acceptor impurity (such as Mg, Zn, C,Be, Ca, and Ba). In order to obtain a p-layer with a high carrierdensity, it is desirable to subject it to annealing at about 400° C. ormore in an inert gas atmosphere (such as nitrogen and argon) afterdoping with an acceptor impurity. Activation by irradiation withelectron beams, microwaves, or light is also available.

[0215] In an embodiment, the layer of a first conductivity type, theactive layer, and the layer of a second conductivity type are parallelto the slant crystal plane slanting to the principal plane of thesubstrate. They are easily formed by crystal growth following theformation of the slant crystal plane. When the crystal layer formsapproximately hexagonal pyramids or prismoids and the slant crystalplane is the S-plane, the light-generating region (consisting of thelayer of a first conductivity type, the active layer, and the layer of asecond conductivity) may be formed entirely or partly on the S-plane.

[0216] With an approximately hexagonal prismoid, the layer of a firstconductivity type, the active layer, and the layer of a secondconductivity type may also be formed on its top face, parallel to theprincipal plane of the substrate. One advantage of light emission by theslant S-plane is that light emerges from the semiconductor withoutmultiple reflection owing to the slant planes. In contrast, withparallel planes, light attenuates due to multiple reflection.) The layerof a first conductivity type (or the cladding layer) may have the sameconductivity type if it is made from the same material as used for thecrystal layer constituting the S-plane. It is also possible to form bycontrolling the density continuously after the crystal layerconstituting the S-plane has been formed. In an embodiment, thestructure may be such that part of the crystal layer constituting theS-plane functions as the layer of a first conductivity type. Also, lightemergence is improved when the plane is not perpendicular to thesubstrate.

[0217] A semiconductor light-emitting device according to an embodimentof the present invention offers improved light emission efficiency byvirtue of desirable crystal properties possessed by the slant crystalplane. The light emission efficiency can be increased if current isinjected only into the S-plane having desirable crystal properties owingto its advantageous uptake for In. The active layer, substantiallyparallel to the S-plane, may have an area larger than that obtained byprojecting the active layer to the principal plane of the substrate orthe underlying layer for growth. The active layer with a large areaincreases the device's emitting surface, thereby leading to a reductionin current density. Moreover, the active layer, with a large area,decreases brightness saturation and hence, increases light emissionefficiency.

[0218] In an embodiment, with the crystal layer in the form of hexagonalpyramid, the S-plane is poor in step state particularly in the vicinityof the apex and the light emission efficiency is low at the apex. Thereason for this is that the hexagonal pyramid is constructed such thateach of its sides consists of four sections extending from its centertoward the apex, left edge, right edge, and base, and the sectionextending toward the apex is very wavy and anomalous growth readilyoccurs in the vicinity of the apex. In contrast, in the two sectionsextending toward both edges, steps are nearly straight and dense and ina very desirable grown state. In the section extending toward the base,steps are slightly wavy but crystal growth is not so anomalous as in thesection extending toward the apex. Thus, in the semiconductorlight-emitting device according to an embodiment of the presentinvention, it is possible to control current injection into the activelayer such that current density is lower in the vicinity of the apexthan in the surrounding areas. The structure to realize the low currentdensity in the vicinity of the apex is such that the electrode is formedat the side of the slope but is not formed at the apex or is such thatthe current block region is formed before the electrode is formed at theapex.

[0219] In an embodiment, electrodes are formed on the crystal layer andthe layer of a second conductivity type, respectively. For reducedcontact resistance, the electrode may be formed on a previously formedcontact layer. These electrodes may be formed by vapor deposition.Accurate vapor deposition is necessary to avoid short-circuiting, whichoccurs as the result of the p-electrode and n-electrode coming intocontact with the crystal layer and the crystal seed layer formed underthe mask.

[0220] A semiconductor light-emitting device according to an embodimentof the present invention includes a substrate and a crystal layer formedthereon, the crystal layer having the slant S-plane (or a planesubstantially equivalent thereto) slanting to the principal plane of thesubstrate and further includes a layer of a first conductivity type, anactive layer, and a layer of a second conductivity type parallel to theS-plane or a plane substantially equivalent thereto which are formed onthe crystal layer. The substrate used herein is not specificallyrestricted so long as it forms a crystal layer having the S-plane or aplane equivalent thereto. It may be the same type of substrate used forthe semiconductor light-emitting device mentioned in the previousembodiment.

[0221] In an embodiment, the crystal layer formed on the substrate hasthe S-plane (or a plane substantially equivalent thereto) slanting tothe principal plane of the substrate. This crystal layer may be formedfrom any material which gives the light-generating region consisting ofthe layer of a first conductivity type, the active layer, and the layerof a second conductivity type parallel to the S-plane or a planesubstantially equivalent thereto. The same type of material mentioned inprevious embodiments may be used. The method for growing the crystallayer and the underlying layer for growth for the crystal layer may alsobe the same as those mentioned in the previously described embodiments.Also, the plane substantially equivalent to the S-plane has a planeorientation inclined toward the S-plane at an angle of about 5 to about6 degrees.

[0222] According to an embodiment of the present invention, it ispossible to use selective growth to form the S-plane or a planesubstantially equivalent thereto. The S-plane is a stable plane which isobtained by selective growth on the C⁺-plane and can be obtainedcomparatively easily with an index of (1-101) in the hexagonal crystalsystem. Just as the C-plane includes the C⁺-plane and the C⁻-plane, sothe S-plane includes the S⁺-plane and the S⁻-plane. In an embodiment,the S⁺-plane is grown on the C⁺-plane GaN and it is referred to as theS-plane unless otherwise stated.

[0223] According to an embodiment of the present invention, asemiconductor light-emitting device is constructed such that the crystallayer has at least the S-plane or a plane substantially equivalentthereto. The crystal layer may be such that the S-plane (or any otherplane substantially equivalent thereto) constitutes the side faces of anapproximately hexagonal pyramid, or the S-plane (or any other planesubstantially equivalent thereto) constitutes the side faces of anapproximately hexagonal prismoid and the C-plane (or any other planesubstantially equivalent thereto) constitutes the top of theapproximately hexagonal prismoid. The approximately hexagonal pyramid orapproximately hexagonal prismoid does not necessarily need to be exactlyhexagonal. It may include those which have one or more missing faces orhave edges which are not straight. The approximately hexagonal pyramidor approximately hexagonal prismoid may be in an elongated shape. Themethod for selective growth is the same as that used in the previouslydescribed embodiments.

[0224] A semiconductor light-emitting device according to an embodimentof the present invention has the layer of a first conductivity type, theactive layer, and the layer of a second conductivity type parallel tothe S-plane or a plane substantially equivalent thereto, which areformed on the crystal layer. The layer of a first conductivity type, theactive layer, and the layer of a second conductivity type are similar tothose explained in the previous embodiments.

[0225] In an embodiment, the layer of a first conductivity type, theactive layer, and the layer of a second conductivity type are parallelto the S-plane or a plane substantially equivalent thereto. They areeasily formed by continuous crystal growth in the place where theS-plane has been formed. When the crystal layer forms approximatelyhexagonal pyramids or prismoids and the slant plane is the S-plane, thelight-generating region (consisting of the layer of a first conductivitytype, the active layer, and the layer of a second conductivity) may beformed entirely or partly on the S-plane. With an approximatelyhexagonal prismoid, the layer of a first conductivity type, the activelayer, and the layer of a second conductivity may also be formed on itstop face parallel to the principal plane of the substrate. One advantageof light emission utilizing the slant S-plane is that light emerges fromthe semiconductor without multiple reflection owing to the slant planes.With parallel planes, light attenuates due to multiple reflection. Thelayer of a first conductivity type (or the cladding layer) may have thesame conductivity type if it is made from the same material as used forthe crystal layer constituting the S-plane. It is also possible to formby controlling the density continuously after the crystal layerconstituting the S-plane has been formed. In an embodiment, thestructure may be such that part of the crystal layer constituting theS-plane functions as the layer of a first conductivity type.

[0226] A semiconductor light-emitting device according to an embodimentof the present invention offers improved light emission efficiency byvirtue of desirable crystal properties possessed by the slant S-plane.The light emission efficiency can be increased if current is injectedonly into the S-plane having desirable crystal properties owing to itsbeneficial uptake for In. The active layer substantially parallel to theS-plane may have an area larger than that obtained by projecting theactive layer to the principal plane of the substrate or the underlyinglayer for growth. The active layer, with a large area, increases thedevice's emitting surface, thereby leading to a reduction in currentdensity. Moreover, the active layer, with a large area, decreasesbrightness saturation and hence, increases light emission efficiency.

[0227] In an embodiment, with the crystal layer in the form of hexagonalpyramid, the S-plane is poor in step state particularly in the vicinityof the apex and the light emission efficiency is low at the apex. Thereason for this is that the hexagonal pyramid is constructed such thateach of its sides consists of four sections extending from its centertoward the apex, left edge, right edge, and base, and the sectionextending toward the apex is very wavy and anomalous growth readilyoccurs in the vicinity of the apex. In contrast, in the two sectionsextending toward both edges, steps are nearly straight and dense and ina very desirable grown state. In the section extending toward the base,steps are slightly wavy but crystal growth is not so anomalous as in thesection extending toward the apex. Thus, in the semiconductorlight-emitting device according to an embodiment of the presentinvention, it is possible to control current injection into the activelayer such that current density is lower in the vicinity of the apexthan in the surrounding areas. The structure to realize the low currentdensity in the vicinity of the apex is such that the electrode is formedat the side of the slope but is not formed at the apex or is such thatthe current block region is formed before the electrode is formed at theapex.

[0228] In an embodiment, electrodes are formed on the crystal layer andthe layer of a second conductivity, respectively. For reduced contactresistance, the electrode may be formed on a previously formed contactlayer. These electrodes may be formed by vapor deposition. Accuratevapor deposition is necessary to avoid short-circuiting, which occurs asthe result of the p-electrode and n-electrode coming into contact withthe crystal layer and the crystal seed layer formed under the mask.

[0229] A semiconductor light-emitting device according to an embodimentof the present invention includes a crystal grown layer having a slantcrystal plane which is formed by selective growth and slants to theprincipal plane of the substrate, an active layer which is formed on thecrystal grown layer and emits light upon injection of current in aprescribed amount, and a reflecting plane or a reflecting region whichis formed approximately parallel to the slant crystal plane and reflectspart of light emerging from the active layer. The same concepts used inprevious embodiments will be applicable to the substrate and crystallayer, the selective growth method of forming the crystal layer, and thebasic constitution of the layer of a first conductivity type, the activelayer, and the layer of a second conductivity type.

[0230] The reflecting plane or reflecting region in the semiconductorlight-emitting device according to an embodiment of the presentinvention is not specifically restricted in its structure so long as itreflects substantially all light generated by the active layer or it iscapable of effective reflection despite slight light transmission. Thisreflecting plane exists (at least partly) approximately parallel to theslant crystal plane. “Approximately parallel to the slant crystal plane”implies that the reflecting plane is either substantially parallel orslightly inclined. The reflecting plane may be a single plane or mayconsist of two or more planes parallel to the slant crystal planecapable of reflecting light generated by the active layer. Thereflecting planes may be constructed such that they overlap in thenormal direction of the slant crystal plane.

[0231] In a semiconductor light-emitting device according to anembodiment of the present invention, the crystal plane itself mayfunction as the reflecting plane. The crystal plane functioning as thereflecting plane reduces scattering and permits light to emergeefficiently. Moreover, when the crystal plane functions as thereflecting plane, it may be constructed such that a metal film, as anelectrode, can be formed after each semiconductor layer (such as theactive layer) has been formed. Thus, the electrode constitutes areflecting film. When the electrode formed on the active layer is usedas the reflecting film, if the active layer is formed such that it islaminated on the slant crystal layer, the electrode can also be formedby itself in conformity with the shape of the crystal grown layer, andfabrication such as etching is unnecessary for the formation of thereflecting film.

[0232] In an embodiment, the reflecting plane, parallel to theabove-mentioned slant crystal plane, for example, may be constructed ofat least two reflecting planes facing each other at an angle smallerthan 180°. These two or more reflecting planes facing each other at anangle smaller than 180° may be two or more planes facing directlyopposite to each other or planes facing each other at other angles witha reflecting plane or a crystal plane interposed between them. Forexample, in the case of a device in which the crystal grown layer ofhexagonal pyramid structure having the S-plane as the side face isformed, they face each other at an angle of about 60° at the apex of thehexagonal pyramid.

[0233] In an embodiment, electrodes are formed on the crystal grownlayer or the first conductive layer and on the layer of a secondconductivity type, respectively. For reduced contact resistance, theelectrode may be formed on a previously formed contact layer. Theseelectrodes may be formed by vapor deposition. Accurate vapor depositionis necessary to avoid short-circuiting, which occurs as the result ofthe p-electrode and n-electrode coming into contact with the crystallayer and the crystal seed layer formed under the mask. If thefundamental structure in the present invention is to be applied to alight-emitting diode, the electrodes may be formed on the first andsecond conductive layers, respectively. Either structure permits lightto emerge from the front or reverse side, as desired. In other words,either structure permits light to emerge from the reverse side if atransparent substrate is used or either structure permits light toemerge from the front side if a transparent electrode is used.

[0234] One feature of a semiconductor light-emitting device according toan embodiment of the present invention is that the emerging light ispartly reflected by the reflecting plane which is parallel to the slantcrystal plane formed by selective growth. Reflection improves the lightemergence efficiency, thereby causing the semiconductor light-emittingdevice to improve in brightness. Since the slant crystal plane as thebase of the reflecting plane can be easily formed by selective growth,the reflecting plane can be obtained by self-forming without additionalsteps, such as etching.

[0235] Another feature of a semiconductor light-emitting deviceaccording to an embodiment of the present invention is that the activelayer has a large area if it is formed by selective growth on a planeslant to the substrate for growth. When the device size is limited, thecurrent injection density per unit area can be reduced for the samebrightness when the active layer in the device has a larger effectivearea. Therefore, the device with a larger effective area has improvedreliability for the same brightness and increased brightness for thesame load on the active layer. In particular, if the difference betweenthe total area of the active area and the area which the selectivelygrown region occupies in the substrate for growth is larger than thearea necessary for contact with at least one electrode, then thatportion of the active layer which is limited by the contact region iscompensated. Consequently, owing to the active layer formed on the slantcrystal plane, a semiconductor light-emitting device according to anembodiment of the present invention is less likely to experience asituation of current concentration even though its size is greatlyreduced.

[0236] A semiconductor light-emitting device according to an embodimentof the present invention includes a substrate, a first grown layer of afirst conductivity type formed on the substrate, a masking layer formedon the first grown layer, and a second grown layer of a firstconductivity type which is formed by selective growth through an openingformed in the masking layer, and which further comprises a claddinglayer of a first conductivity type parallel to the crystal plane of thesecond grown layer, an active layer, and a cladding layer of a secondconductivity type, part or all of which cover the masking layersurrounding the opening. The substrate used in this embodiment is notspecifically restricted so long as it can form the crystal layer whichhas a slant crystal plane slating to the principal plane of thesubstrate. It may be the same type used for the previous embodiments.

[0237] In an embodiment, the substrate is formed the grown layer whichconsists of a first grown layer (which is arranged under the maskinglayer) and a second grown layer which is formed and grown from theopening in the masking layer. These first and second grown layers are ofa first conductivity type, but they are not specifically restricted solong as they permit the light-generating region (which consists of alayer of a first conductivity type, an active layer, and a layer of asecond conductivity type) to be formed on the plane parallel to thecrystal plane of the second grown layer. The first and second grownlayers may be formed from a compound semiconductor, preferably that of awurtzite structure.

[0238] In an embodiment, the grown layer may be formed from a group IIIbased compound semiconductor, a BeMgZnCdS based compound semiconductor,a BeMgZnCdO based compound semiconductor, or the like. It may be formedalso from a gallium nitride (GaN) based compound semiconductor, analuminum nitride (AlN) based compound semiconductor, an indium nitride(InN) based compound semiconductor, an indium gallium nitride (InGaN)based compound semiconductor, an aluminum gallium nitride (AlGaN) basedcompound semiconductor, the like or combinations thereof. Nitridesemiconductors such as a gallium nitride based compound semiconductorare preferred.

[0239] It should be noted that in the present invention, InGaN, AlGaN,GaN, and the like do not necessarily imply nitride semiconductors ofternary or binary mixed crystals alone. InGaN, for example, may containa trace amount of Al and other impurities which do not affect thefunction of InGaN. Such compound semiconductors are within the scope ofthe present invention. In this specification, “nitride” means a compoundcomposed of any of B, Al, Ga, In, and Ta as group III elements andmainly N as group V elements. However, “nitride” in this specificationalso includes those which have their bandgap reduced by incorporationwith a trace amount of As and P.

[0240] In an embodiment, the grown layer can be formed by chemical vapordeposition of various kinds, such as metal organic chemical vapordeposition (MOCVD) including, for example, metal organic vapor phaseepitaxy (MOVPE), molecular beam epitaxy (MBE), hydride vapor phaseepitaxy (HVPE), and the like. In an embodiment, MOCVD is preferredbecause it rapidly yields a grown layer with advantageous crystalproperties. The MOCVD method commonly employs alkyl metal compounds,such as TMG (trimethylgallium) or TEG (triethylgallium) as a Ga source,TMA (trimethylaluminum) or TEA (triethylaluminum) as an Al source, andTMI (trimethylindium) or TEI (triethylindium) as an In source. It alsoemploys ammonia gas or hydrazine gas as a nitrogen source and othergases as an impurity source, for example, silane gas for Si, germane gasfor Ge, Cp₂Mg (cyclopentadienylmagnesium) for Mg, and DEZ (diethylzinc)for Zn. Usually, MOCVD is carried out by feeding the gases to thesurface of the substrate which is heated at about 600° C. or above, sothat the gases decompose to give an InAlGaN based compound semiconductorby epitaxial growth.

[0241] The first grown layer, in an embodiment, may be a gallium nitridelayer or an aluminum nitride layer. It may also be a combination of alow-temperature buffer layer and a high-temperature buffer layer, or acombination of a buffer layer and a crystal seed layer (functioning as acrystal seed). Forming the grown layer from the low-temperature bufferlayer poses a problem that polycrystals are liable to precipitate on themask. This problem is solved by forming a crystal seed layer and thengrowing thereon a plane differing from the substrate. Thus, it ispossible to grow crystals having advantageous crystal properties. Withselective growth for crystal growing, it is necessary to grow crystalsfrom the buffer layer if there exists no crystal seed layer. Selectivegrowth from the buffer layer causes crystals to grow from the part wherethe crystal growth is not required. Consequently, the crystal seed layerpermits crystals to grow selectively in the region where crystal growthis necessary.

[0242] In an embodiment, the buffer layer is intended to relieve latticemismatch between the substrate and the nitride semiconductor. Therefore,there may be an instance where the buffer layer is not formed if thesubstrate has a lattice constant close to that of the nitridesemiconductor. For example, there may be an instance where an AlN bufferlayer is formed on SiC without lowering temperature or an AlN or GaNbuffer layer is formed on a Si substrate without lowering temperature.Thus, it is also possible to form GaN of a desirable quality. Thestructure without any buffer layer is acceptable if the substrate is GaNor a suitable material.

[0243] According to an embodiment of the present invention, the secondgrown layer is formed by selective growth and consequently it ispossible to obtain the slant plane, slanting to the principal plane ofthe substrate. In general, depending on the selection of the principalplane of the substrate, it is possible to form a slant plane selectedfrom the (1-100) plane [M-plane], the (1-101) plane [S-plane], the(11-20) plane [A-plane], the (1-102) plane [R-plane], the (11-23) plane[N-plane], the (11-22) plane, the like and combinations thereof when theprincipal plane of the substrate is the (0001) plane [C-plane] of awurtzite structure.

[0244] In an embodiment, the S-plane and the (11-22) plane arepreferred. Naturally, equivalent crystal planes may also be usedincluding those which have a plane orientation inclined at an angle ofabout 5 to about 6 degrees with respect to the S-plane and the (11-22)plane. In particular, the S-plane is a stable plane which is obtainedwhen selective growth is carried out on the C⁺-plane. The S-plane can beobtained comparatively easily, and its index is (1-101) in the hexagonalcrystal system. Just as the C-plane includes the C⁺-plane and theC⁻-plane, the S-plane includes the S⁺-plane and the S⁻-plane. In thisspecification, the S⁺-plane is grown on the C⁺-plane GaN and it isreferred to as the S-plane unless otherwise stated. Additionally, of theS-planes, the S⁺-plane is stable.

[0245] When the crystal layer is formed from a gallium nitride basedcompound semiconductor, as mentioned above, the number of bonds from Gato N is 2 or 3 on the S-plane or S⁺-plane. This number is second to thaton the C-plane. Since the C⁻-plane cannot be obtained on the C⁺-plane,in practice, the number of bonds on the S-plane is the largest. Forexample, in the case where a nitride is grown on a sapphire substratehaving the C-plane as the principal plane, the nitride of a wurtzitestructure has a surface of C⁺-plane. However, it is possible to form theS-plane if selective growth is employed. On the plane parallel to theC-plane, the bond of N (which easily releases itself) combines with onebond of Ga, whereas on the inclined S-plane, it combines with at leastone bond. This causes the effective V/III ratio to increase, therebyimproving the crystal properties of the laminate structure. In addition,growth in the direction different from the orientation of the substratebends dislocations extending from the substrate, thereby favorablydecreasing defects.

[0246] According to an embodiment of the present invention, asemiconductor light-emitting device may be constructed such that thesecond grown layer by selective growth slants to the principal plane ofthe substrate. The second grown layer may be such that the S-plane (orany other plane substantially equivalent thereto) constitutes the sidefaces of an approximately hexagonal pyramid, or the S-plane (or anyother plane substantially equivalent thereto) constitutes the side facesof an approximately hexagonal prismoid and the C-plane (or any otherplane substantially equivalent thereto) constitutes the top plane of theapproximately hexagonal prismoid. The approximately hexagonal pyramid orprismoid does not necessarily need to be exactly hexagonal. It mayinclude those which have one or more missing faces. The edge between thecrystal planes of the crystal layer does not necessarily need to bestraight. Also, the approximately hexagonal pyramid or prismoid may bein an elongated shape.

[0247] In actuality, selective growth is accomplished in an embodimentby using a selectively made opening in the masking layer formed on thefirst grown layer. The opening in the masking layer may take on anyshape such as a circle, a square, a hexagon, a triangle, a rectangle, arhombus, a strip, a lattice, the like and combinations thereof. Themasking layer in an embodiment is formed from a dielectric material suchas silicon oxide, silicon nitride and the like. The masking layer mayhave a thickness ranging from about 0.1 μm to about 5 μm (preferablyfrom about 0.1 μm to about 1.0 μm) so as to relieve steps in thevicinity of the active layer and electrode. The approximately hexagonalpyramid or prismoid in an elongated shape may be formed if the opening(window region) in the masking layer is in an elongated shape.

[0248] In an embodiment, if the window region in the masking layer forselective growth is a circle of about 10 μm in diameter (or a hexagonwhose one side coincides with the (1-100) direction or (11-20)direction), it is possible to easily form a selectively grown regionwhich is about twice as large as the window region. Also, the S-plane,in a direction different from the substrate, produces the effect ofbending or isolating dislocations, thereby contributing to reduction inthe density of dislocations.

[0249] Observation by cathode luminescence on the grown hexagonalprismoids indicates that the S-plane formed as the second grown layerhas desirable crystal quality and is superior to the C⁺-plane in lightemission efficiency. Growing the InGaN active layer at about 700° C. toabout 800° C. makes ammonia decompose slowly and hence, requires morenitrogen species. Observation with an AFM revealed that the surface hasregular steps suitable for InGaN uptake. It was also found that theMg-doped layer has a good surface state owing to the S-plane and thatthe doping condition is considerably different. In general, the Mg-dopedlayer has a grown surface in a poor state when observed by an AFM.Observation by microscopic photoluminescence mapping (which has aresolving power of about 0.5 μm to about 1 μm) revealed that theS-plane, formed by selective growth, is uniform. The S-plane formed onthe C⁺-plane by the ordinary process has irregularities at a pitch ofabout 1 μm. Also, observation with an SEM revealed that the slope of theS-plane is smoother than that of the C⁺-plane.

[0250] If selective growth is carried out by using a mask such thatcrystals grow only over the opening of the mask, crystals do not grow inthe lateral direction. Thus, it is possible to employ microchannelepitaxy to make crystals to grow in the lateral direction, extendingbeyond the window region. It is known that growing in the lateraldirection by microchannel epitaxy readily avoids threading dislocationsand hence reduces dislocations. Thus, growing in the lateral directiongives an enlarged light-generating region and contributes to uniformcurrent flow and reduced current density.

[0251] A semiconductor light-emitting device according to an embodimentof the present invention has a cladding layer of a first conductivitytype, an active layer, and a cladding layer of a second conductivitytype which are formed parallel to the crystal plane of second grownlayer. The layer of a first conductivity type, the active layer, and thelayer of a second conductivity type are similar to those explained inprevious embodiments.

[0252] In a semiconductor light-emitting device according to anembodiment of the present invention, the cladding layer of a firstconductivity type, the active layer, and the cladding layer of a secondconductivity type extend entirely or partly to the masking layersurrounding the opening. One advantage of the structure in which themasking layer partly remains unremoved is that the support under thelaterally grown part does not disappear. One advantage of the structurein which the masking layer entirely remains unremoved is that astructural offset(s) or gap(s) due to selective growth can be relievedand the masking layer functions as a supporting layer for the firstgrown layer, thereby keeping the n- and p-electrodes apart andpreventing short-circuiting, even when the substrate is peeled off bylaser irradiation.

[0253] Another semiconductor light-emitting device according to anembodiment of the present invention is constructed such that the secondgrown layer is entirely covered by the cladding layer of a firstconductivity type, the active layer, and the cladding layer of a secondconductivity type. This structure can be formed easily because thesecond grown layer assumes the slant crystal plane due to selectivegrowth. In other words, when the active layer, parallel to the principalplane of the substrate, is formed, the end is exposed to air. However,it is possible to cover the end by utilizing the slant crystal plane.Since the second grown layer is entirely covered, the active layer isprotected from oxidation and other degradation. Moreover, it producesthe effect of increasing the light emission area.

[0254] Further, another semiconductor light-emitting device according toan embodiment of the present invention is constructed such that each endof the cladding layer of a first conductivity type, the active layer,and the cladding layer of a second conductivity type is in directcontact with the masking layer. This structure can be formed easilybecause the second grown layer assumes the slant crystal plane due toselective growth. Since each end is in direct contact with the maskinglayer and covers the active layer, the active layer is previouslyprotected from oxidation and other degradation. Moreover, it producesthe effect of increasing the light emission area.

[0255] A semiconductor light-emitting device according to an embodimentof the present invention offers improved light emission efficiencybecause the crystal plane has advantageous crystal properties. The lightemission efficiency can be increased if current is injected only intothe S-plane having beneficial crystal properties owing to its desirableuptake for In. The active layer substantially parallel to the S-planemay have an area larger than that obtained by projecting the activelayer to the principal plane of the substrate or the first grown layer.The active layer, with a large area, increases the device's lightemission surface, thereby leading to a reduction in current density.Moreover, the active layer, with a large area, decreases brightnesssaturation and hence, increases light emission efficiency.

[0256] In an embodiment, electrodes are formed on the second grown layerand the cladding layer of a second conductivity type, respectively. Forreduced contact resistance, the electrode may be formed on a previouslyformed contact layer. These electrodes may be formed by vapordeposition. Accurate vapor deposition is necessary to avoidshort-circuiting, which occurs as the result of the p-electrode andn-electrode coming into contact with the layer and the first grown layerformed under the mask.

[0257] A semiconductor light-emitting device according to an embodimentof the present invention includes a layer of a first conductivity typeand a layer of a second conductivity type and an active layer which isheld between the layers and is formed by selective growth not parallelto the principal plane of the substrate for growth, with the area of theactive layer being larger than that of a window region used at the timeof selective growth on the substrate or larger than the projected areaobtained by projecting the selectively grown crystal layer to thesubstrate for growth in its normal direction. Similar concepts used inprevious embodiments will be applicable to the substrate and crystallayer, the method of forming the crystal layer, and the basicconstitution of the layer of a first conductivity type, the activelayer, and the layer of a second conductivity type.

[0258] A semiconductor light-emitting device according to an embodimentof the present invention is basically constructed such that the activelayer is formed as a slant plane by selective growth. For the maximumeffect, it is desirable that the basic device size be equal to thethickness of the crystal grown layer or about 50 μm or less. The smallerthe device size, the better the result. However, the basic structure isapplicable to any device regardless of size so long as it is arrangedone dimensionally or two dimensionally in a single device. Inparticular, a semiconductor light-emitting device according to anembodiment of the present invention produces its effect when the firstconductive layer with high resistance needs a high-density contact forelectrodes or the second conductive layer needs as large a contact areaas possible.

[0259] In a semiconductor light-emitting device according to anembodiment of the present invention, the active layer is held between alayer of a first conductivity type and a layer of a second conductivitytype, and the active layer is not parallel to the principal plane of thesubstrate for growth. The layer of a first conductivity type is acladding layer of p-type or n-type, and the layer of a secondconductivity type is a cladding layer of an opposite type. For example,if the crystal layer having the C-plane is formed from a silicon-dopedgallium nitride based compound semiconductor layer, the semiconductorlight-emitting device may take a double heterojunction structureconsisting of an n-cladding layer of silicon-doped gallium nitridecompound semiconductor, an active layer of InGaN, and a p-type claddinglayer of magnesium-doped gallium nitride based compound semiconductorwhich are formed sequentially one over another. Another possiblestructure is such that the active layer of InGaN is held between twoAlGaN layers. The active layer may be of single bulk layer structure.Alternatively, it may be of single quantum well (SQW) structure, doublequantum well (DQW) structure, or multiple quantum well (MQW) structure.The quantum well structure may use a barrier layer for separation ofquantum wells, if necessary. The light-emitting device having an activelayer of InGaN is easy to produce and has desirable light emissioncharacteristics. Moreover, InGaN readily crystallizes with advantageouscrystal properties on the S-plane from which nitrogen atoms hardlyrelease themselves, thereby increasing the light emission efficiency.

[0260] Additionally, the nitride compound semiconductor tends to becomen-type due to nitrogen holes which occur in its crystal even though itis not doped. However, it can be deliberately made n-type having adesired carrier density if it is doped with an ordinary donor impurity(such as Si, Ge, and Se) during crystal growth. Also, the nitridesemiconductor can be made p-type by doping with an acceptor impurity(such as Mg, Zn, C, Be, Ca, and Ba).

[0261] In an embodiment, the layer of a first conductivity type, theactive layer, and the layer of a second conductivity type are formed onthe crystal grown layer slanting to the principal plane of the substratefor growth. The active layer, not parallel to the principal plane of thesubstrate for growth, is easily formed by crystal growth following theformation of the slant crystal plane. If the active layer is formed onthe crystal planes extending toward both sides from the ridge line, theresulting active layer has a bent part (e.g., bending from the S-planeto C-plane or bending from the S-plane to the M-plane). When the crystalgrown layer forms an approximately hexagonal pyramid or prismoid and thesurface of the slant crystal grown layer is the S-plane, thelight-generating region (consisting of the layer of a first conductivitytype, the active layer, and the layer of a second conductivity) may beformed entirely or partly on the S-plane.

[0262] With an approximately hexagonal prismoid, it is possible to formthe layer of a first conductivity type, the active layer, and the layerof a second conductivity type also on the plane parallel to theprincipal plane of the substrate, for example, on the C-plane. Oneadvantage of light emission by the slant S-plane is that light emergesfrom the semiconductor without multiple reflection owing to the slantplanes. In contrast, with parallel planes, light attenuates due tomultiple reflection. The layer of a first conductivity type (or thecladding layer) may have the same conductivity type if it is made fromthe same material as used for the crystal layer constituting theS-plane. It is also possible to form by controlling the densitycontinuously after the crystal layer constituting the S-plane has beenformed. In an embodiment, the structure may be such that part of thecrystal layer constituting the S-plane functions as the layer of a firstconductivity type.

[0263] A semiconductor light-emitting device according to an embodimentof the present invention offers improved light emission efficiencybecause the slant crystal plane has desirable crystal properties. Thelight emission efficiency can be increased if current is injected onlyinto the S-plane having desirable crystal properties owing to itsadvantageous uptake for In. The active layer, substantially parallel tothe S-plane, may have an area larger than that obtained by projectingthe active layer to the principal plane of the substrate or theunderlying layer for growth. The active layer with a large areaincreases the device's emitting surface, thereby leading to a reductionin current density. Moreover, the active layer, with a large area,decreases brightness saturation and hence, increases light emissionefficiency.

[0264] In an embodiment, electrodes are formed on the crystal grownlayer or the first conductive layer and on the layer of a secondconductivity type, respectively. For reduced contact resistance, theelectrodes may be formed on a previously formed contact layer. Theseelectrodes may be formed by vapor deposition. Accurate vapor depositionis necessary to avoid short-circuiting, which occurs as the result ofthe p-electrode and n-electrode coming into contact with the crystallayer and the crystal seed layer formed under the mask. If thefundamental structure in the present invention is applied to alight-emitting diode, the electrodes may be formed respectively on thefirst and second conductive layers. Either structure permits light toemerge from the front or reverse side as desired. In other words, eitherstructure permits light to emerge from the reverse side if a transparentsubstrate is used or either structure permits light to emerge from thefront side if a transparent electrode is used.

[0265] One feature of a semiconductor light-emitting device according toan embodiment of the present invention is that the active layer has alarge area if it is formed by selective growth on a plane not parallelto the substrate for growth. When the device size is limited, thecurrent injection density per unit area can be reduced for the samebrightness when the active layer in the device has a larger effectivearea. Therefore, the device with a larger effective area has improvedreliability for the same brightness and increased brightness for thesame load on the active layer. In particular, if the difference betweenthe total area of the active area and the area which the selectivelygrown region occupies on the substrate for growth is larger than thearea necessary for contact with at least one electrode, then thatportion of the active layer which is limited by the contact region iscompensated. Consequently, a semiconductor light-emitting deviceaccording to an embodiment of the present invention is less likely toexperience a situation of current concentration even though its size isgreatly reduced.

[0266] In an embodiment, assuming that the crystal grown layer takes onthe shape of a ridge with a triangular cross section and the slant planeof the crystal grown layer slants to the principal plane of thesubstrate at an angle of θ. It should be understood that the effectivearea of the active layer is 1/cosθ times larger (at the maximum) thanthe projected area obtained by projecting the entire region of theactive layer to the substrate for growth in its normal direction. Theeffective area necessarily becomes large if the crystal grown layer isformed (in the shape of polygonal pyramid or prismoid as well as theridge with a triangular cross section) by selective growth and then theactive layer is formed thereon which is not parallel to the substrate.Additionally, the projected area is equal to the area occupied on theprincipal plane of the substrate and is also equal to the shadow of thecrystal grown layer which would be formed if light is projected towardthe principal plane of the substrate in its normal direction.

[0267] In addition, the area of the active layer can be made larger thanthe area of the substrate for growth if the region not used for crystalgrowth is minimized and the active layer is separated from its adjacentones by a growth inhibiting film (such as a masking layer) and grown tothe maximum extent such that adjacent stable planes do not come intocontact with each other. However, the maximum area attained by a singlegrowth is equal to the area of the substrate used for growth. Theeffective area of the active layer is reduced further after theelectrodes and device separating grooves have been added. Therefore, asatisfactory effect is obtained even though the total area of the activelayer is not necessarily larger than the area of the substrate forgrowth.

[0268] In an embodiment, if the effective area of the active layer ismade larger than the area of the window region used at the time ofselective growth on the substrate for growth, or lager than theprojected area obtained by projecting the crystal grown layer resultingfrom selective growth to substrate in its normal direction, then it ispossible to reduce the density of current injected into the activelayer, thereby improving the reliability of the device. Also, if theeffective area of the active layer is made larger than the sum of theprojected area of the selective grown region toward the substrate forgrowth in its normal direction and the contact area of at least oneelectrode and the conductive layer, it is possible to reduce the densityof current being injected into the active layer, thereby improving thereliability of the device. In particular, if the difference between thetotal area of the active layer and the projected area of the selectivelygrown region toward the substrate for growth is larger than the areanecessary for contact with at least one electrode, then that portion ofthe active layer which is limited by the contact region is compensated.

[0269] Assuming a light-emitting diode device, for example, having thesize of a 30 μm square, is produced. The region in which the firstelectrode comes into contact with the underlying conductive layer (whichis the first conductive layer) is approximately 20 μm×5 μm and theregion for selective growth in which the active layer can be placed isapproximately 20 μm square at the largest. Therefore, by making thetotal area of the active layer equal to or larger than 500 μm²,it ispossible to obtain the device structure according to an embodiment ofthe present invention. If a quadrangular pyramid (with a slope angle of45° and a base side of 20 μm) is formed in the region for selectivegrowth and the active layer is formed thereon uniformly, the total areaof the active layer is 20 μm×20 μm/cos 45°=566 μm². Thus, the effectivearea of the active layer is sufficiently large compared with the contactarea. Moreover, it is apparent that the effect will be better if theangle of the slope is larger. In view of the fact that the (1-101)stable for the (0001) of a wurtzite structure is about 62° and the (111)plane stable for the (001) plane of zincblende is about 54.7°, thepresent invention ensures satisfactory reliability by expanding theregion for the active layer.

[0270] It is possible to construct an image display unit or lightingsystem by arranging, in an array, a plurality of semiconductorlight-emitting devices according to an embodiment of the presentinvention. If devices corresponding to three primary colors are arrangedin an array capable of scanning, the resulting display unit will have asmall area because the electrode has a reduced area owing to the use ofthe S-plane.

EXAMPLES

[0271] The present invention will be described in more detail withreference to the following examples. Each example corresponds to anindividual production process and each device resulting from theproduction process is a semiconductor light-emitting device having astructure defined according to an embodiment of the present invention.The production process is described first and then the device resultingfrom the production process is subsequently described. Variousmodifications and changes may be made in the semiconductorlight-emitting device without departing from the spirit and scope of theinvention. The following examples are not intended to restrict the scopeof the invention.

Example 1

[0272] This example demonstrates a semiconductor light-emitting devicewhich has a crystal layer formed by selective growth directly on asapphire substrate. Additionally, the crystal layer includes a crystalsurface having the S-plane as the slant crystal plane (i.e. the crystalsurface plane that diagonally intersects the principal plane of thesubstrate). Its production process and structure will be described withreference to FIGS. 3A to 9.

[0273] The sapphire substrate 10 has the C⁺-plane as its principal plane11 (i.e. the substrate surface plane). On the entire surface of thesapphire substrate 10 is formed the masking layer 12 (about 100 nm toabout 500 nm thick) of SiO₂ or SiN. In the masking layer 12 is formedthe opening 13 (about 100 μm) by photolithography and etching withhydrofluoric acid based compound (see FIGS. 3A and 3B). In this Example,the opening 13 is in an approximately rectangular shape, but the size ofthe opening may be changed according to the characteristics of thelight-emitting device to be produced.

[0274] Then, selective growth is carried out in two stages. First, athin GaN layer or a low-temperature buffer layer (about 20 mn to about30 nm thick) is grown at a low temperature of about 500° C. Secondly,the growing temperature is raised to about 1000° C. so as to form thesilicon-doped GaN layer 14, as shown in FIG. 4A and 4B. Thesilicon-doped GaN layer 14 grows in the opening 13 in the masking layer12, but it gradually expands in the lateral direction while it is keptat about 1000° C. in a hydrogen atmosphere.

[0275] On the silicon-doped GaN layer 14 a masking layer 15 is formed.Subsequently, an approximately round opening 16 is formed byphotolithography and etching (see FIGS. 5A and 5B). The silicon-dopedGaN layer 14 is allowed to grow further through the opening 16 until thesilicon-doped GaN layer 17 grows in the shape of a hexagonal pyramid.The surface of the crystal layer in the shape of the hexagonal pyramidis covered by the S-plane, that is, the (1-101) plane according toMiller indices of a hexagonal system. If the growing time isinsufficient or if different growing conditions are employed, thesilicon-doped GaN layer 17 may take the shape of a hexagonal prismoid inwhich the top plane is the C⁺-plane, parallel to the principal plane ofthe substrate. In this example, however, the silicon-doped GaN layer 17is grown until it takes the shape of a hexagonal pyramid. After thelapse of sufficient growing time, the side faces of the hexagonalpyramid of the silicon-doped GaN layer 17 are covered with the S-plane.It is necessary that the opening 16 is sufficiently apart from adjacentopenings.

[0276] It should be noted that the S-plane is intended to include one ormore of the planes relating to the family of planes corresponding to the(1-101) plane. In an embodiment, the S-plane includes the planescorresponding to each side face of the hexagonal pyramid as shown inthis example. For example, in addition to the (1-101) plane, thehexagonal pyramid has side faces corresponding to the (10-11),(01-11(1101), (-1011), and (0-111) planes.

[0277] After the silicon-doped GaN layer 17 has grown in the shape of ahexagonal pyramid, growing is continued until the hexagonal pyramidbecomes about 15 μm to about 20 μm wide (with one side being about 7.5μm to about 10 μm long). The height of the hexagonal pyramid is about 10μm to about 16 μm, which is about 1.6 times the side of the hexagonalpyramid. This size is merely exemplary, and the width equal to orsmaller than 10 μm may be acceptable. The silicon-doped GaN layer 17 isgrown further. Subsequently, the InGaN layer 18 is grown at a reducedgrowing temperature. The thickness of the InGaN layer 18 is about 0.5 nmto about 3 nm. Then, the magnesium-doped GaN layer 19 is grown at anincreased growing temperature, as shown in FIGS. 6A and 6B. There may bean instance where a quantum well layer (or a multiple quantum welllayer) of (Al)GaN/InGaN is formed, or there may be another instancewhere a multilayer structure is formed with GaN or InGaN functioning asthe guide layer. In such a case, it is desirable to grow the AlGaN layerdirectly on the InGaN layer.

[0278] Subsequently, etching is performed on part of the epitaxiallygrown layer until the silicon-doped GaN layer 14 is exposed. In theremoved part 21, the n-electrode 20 (Ti/Al/Pt/Au) is formed by vapordeposition. On the outermost surface of the previously grown hexagonalpyramid, the p-electrode 22 (Ni/Pt/Au or Ni(Pd)/Pt/Au) is formed byvapor deposition (see FIGS. 7A and 7B). These vapor depositions shouldbe carried out accurately so as to prevent the p-electrode andn-electrode from coming into contact with the silicon-doped GaN layer 17(in the form of hexagonal pyramid) and the silicon-doped GaN layer 14(formed under the mask), thereby preventing short-circuiting. Then,individual light-emitting devices are separated by RIE (reactive ionetching) or dicing (i.e., separating the devices with an opticalmechanism, a mechanical mechanism, or the like), as shown in FIGS. 8Aand 8B. Thus, the light-emitting device in this example is completed.

[0279] The light-emitting device produced by the above-mentioned processhas a structure as shown in FIG. 9. It is composed mainly of thesapphire substrate 10 whose principal plane is the C⁺-plane, thesilicon-doped GaN layer 14 as a crystal seed layer, and thesilicon-doped GaN layer 17 as a crystal layer. The silicon-doped GaNlayer 17 has the slant S-plane, slanting to the principal plane of thesubstrate. The InGaN layer 18 (as an active layer) is parallel to theS-plane. On the InGaN layer 18 is formed the magnesium-doped GaN layer19 as a cladding layer. The p-electrode 22 is formed on themagnesium-doped GaN layer 19. The n-electrode 20 is formed in the openregion at the side portion of the hexagonal pyramid, and it is connectedto the silicon-doped GaN layer 17 through the silicon-doped GaN layer14.

[0280] The light-emitting device in this example has an advantage that,owing to the S-plane slanting to (i.e., diagonally intersecting) theprincipal plane of the substrate, the number of bonds from nitrogenatoms to gallium atoms increases, which increases the effective V/IIIratio. Therefore, the resulting light-emitting device has improvedperformance. In addition, the fact that the principal plane of thesubstrate is the C⁺-plane and hence, the S-plane is different from theprincipal plane of the substrate tends to decrease defects anddislocations extending from the substrate bend. The slant crystal planeslanting to the principal plane of the substrate prevents multiplereflection, thereby permitting the generated light to emergeefficiently.

Example 2

[0281] This example demonstrates a semiconductor light-emitting devicewhich has a crystal layer (having the S-plane slanting to the principalplane of the substrate) formed on a crystal seed layer isolated from asapphire substrate. Its production process and structure will bedescribed with reference to FIGS. 10A to 17B.

[0282] On the sapphire substrate 30, whose principal plane is theC⁺-plane, is formed a buffer layer of AlN or GaN at a low temperature ofabout 500° C. Then, with the temperature raised to about 1000° C., thesilicon-doped GaN layer 31 is formed. On the entire surface of thesilicon-doped GaN layer 31 is formed a masking layer (about 100 nm toabout 500 nm thick) of SiO₂ or SiN. The masking layer is removed byphotolithography and etching with hydrofluoric acid based compoundexcept for the round masking part 32 (about 10 μm in diameter), as shownin FIGS. 10A and 1B. Etching is performed so that the principal plane ofthe sapphire substrate 30 is exposed, as shown in FIGS. 11A and 11B. Asa result, the cylindrical silicon-doped GaN layer 31 in conformity withthe shape of the masking part 32 remains.

[0283] Then, the masking part 32 is removed and crystal growing is againcarried out, that is, the silicon-doped GaN layer 33 is grown at araised growing temperature of about 1000° C. The silicon-doped GaN layer33 grows on the silicon-doped GaN layer 31 remaining unetched. Aftercontinued growing, the silicon-doped GaN layer 33 forms a hexagonalpyramid surrounded by the S-plane slanting to the principal plane of thesubstrate. This hexagonal pyramid grows in proportion to the growingtime. The GaN layer 31 should be sufficiently apart from adjacent layersso that the fully grown GaN layer 33 does not interfere with adjacentlayers and the completed devices are separated from each other withsufficient margins.

[0284] The hexagonal pyramid grows to such an extent that the width isabout 15 μm to about 20 μm (with one side being about 7.5 μm to about 15μm long) and the height is about 10 μm to about 16 μm, which is about1.6 times the side of the hexagonal pyramid, as with Example 1. Thissize is merely exemplary, and the width equal to or smaller than 10 μmmay be acceptable. After the hexagonal pyramid surrounded by the slantS-plane has been formed, as shown in FIGS. 12A and 12B, the silicondoped GaN layer is grown and then the InGaN layer 34 is grown at a lowergrowing temperature. Then, with the growing temperature raised, themagnesium-doped GaN layer 35 is grown, as shown in FIGS. 13A and 13B.The thickness of the InGaN layer 34 is about 0.5 nm to about 3 nm. Theremay be an instance where a quantum well layer (or a multiple quantumwell layer) of (Al)GaN/InGaN is formed, or there may be another instancewhere a multilayer structure is formed with GaN or InGaN functioning asthe guide layer. In such a case, it is desirable to grow the AlGaN layerdirectly on the InGaN layer.

[0285] The InGaN layer 34 (as an active layer) and the magnesium-dopedGaN layer 35 (as a p-type cladding layer) are partly removed at the sideclose to the substrate, so that the silicon-doped GaN layer 33 is partlyexposed. In the removed part, close to the substrate, the Ti/Al/Pt/Auelectrode (as the n-electrode 36) is formed by vapor deposition. On theoutermost surface of the hexagonal pyramid, the Ni/Pt/Au or Ni(Pd)/Pt/Auelectrode (as the p-electrode 37) is formed by vapor deposition (seeFIGS. 14A and 14B). These vapor depositions should be carried outaccurately so as to prevent the electrodes from coming into contact witheach other, thereby preventing short-circuiting, as with Example 1.

[0286] After the electrodes 36 and 37 have been formed, individuallight-emitting devices are separated by RIE (reactive ion etching) ordicing, as shown in FIGS. 15A and 15B. Thus, the light-emitting devicein this example is completed.

[0287] The light-emitting device produced by the above-mentioned processhas a structure as shown in FIG. 16. It is composed mainly of thesapphire substrate 30 whose principal plane is the C⁺-plane and thesilicon-doped GaN layer 33 as a crystal layer. The silicon-doped GaNlayer 33 has the slant S-plane slanting to the principal plane of thesubstrate. The InGaN layer 34 (as an active layer) is parallel to theS-plane. On the InGaN layer 34 is formed the magnesium-doped GaN layer35 as a cladding layer. The p-electrode 37 is formed on themagnesium-doped GaN layer 35. The n-electrode 36 is formed in the openregion at the vicinity of the substrate on the S-plane of the hexagonalpyramid, and it is connected directly to the silicon-doped GaN layer 33.

[0288] The light-emitting device in this example (which is constructedas mentioned above) has an advantage that, like the light-emittingdevice in Example 1, owing to the S-plane slanting to the principalplane of the substrate, the number of bonds from nitrogen atoms togallium atoms increases, which increases the effective V/III ratio.Therefore, the resulting light-emitting device has improved performance.In addition, the fact that the principal plane of the substrate is theC⁺-plane and hence, the S-plane is different from the principal plane ofthe substrate tends to decrease defects and dislocations extending fromthe substrate bend. The slant S-plane slanting to the principal plane ofthe substrate prevents multiple reflection, thereby permitting thegenerated light to emerge efficiently.

[0289] Additionally, in this example, the silicon-doped GaN layer isetched first so that the sapphire substrate 30 is exposed. However,etching may be carried out in such a way that a sufficiently high stepis formed in the silicon-doped GaN layer. Growing on the thus formedsilicon-doped GaN layer (as a crystal seed layer) readily gives thedesired hexagonal pyramid. The device produced in this manner is shownin FIGS. 17A and 17B. The step 39 is formed in the silicon-doped GaNlayer 38 formed on the sapphire substrate 30. The silicon-doped GaNlayer as a crystal layer in the shape of hexagonal pyramid grows fromthe projection part. On the silicon-doped GaN layer are formed the InGaNlayer 34 (as an active layer), the magnesium-doped GaN layer 35 (as ap-type cladding layer), the p-electrode 37, and the n-electrode 36.Light with a desired wavelength is extracted from the InGaN layer 34.

Example 3

[0290] This example demonstrates a semiconductor light-emitting devicein which the crystal layer in the shape of hexagonal pyramid (which hasthe S-plane slanting to the principal plane of the substrate) is formedwithin the window region for the selective mask. Its production processand structure will be described with reference to FIGS. 18A to 23.

[0291] On the sapphire substrate 40, whose principal plane is theC⁺-plane, is formed a buffer layer of AlN or GaN at a low temperature ofabout 500° C. Then, with the temperature raised to about 1000° C., thesilicon-doped GaN layer 41 is formed. On the entire surface of thesilicon-doped GaN layer 41 is formed the masking layer 42 (about 100 nmto about 500 nm thick) of SiO₂ or SiN. In the masking layer 42 is formeda round opening (about 10 μm in diameter) as the window region 43 byphotolithography and etching with hydrofluoric acid based compound, asshown in FIGS. 18A and 18B. The size of the opening varies depending onthe light-emitting device desired.

[0292] Then, the silicon-doped GaN layer 44 is grown again at a growingtemperature of about 1000° C. In the beginning, the silicon-doped GaNlayer 44 grows from the round window region 43. After growing for awhile, it takes the shape of a hexagonal pyramid surrounded by S-planesor (1-101) planes. It may take the shape of a hexagonal prismoid underdifferent growing conditions. Under adequately controlled growingconditions, the silicon-doped GaN layer 44 grows until the hexagonalpyramid (covered with S-planes) almost fills the window region in theselective mask. With the growing temperature lowered, the InGaN layer 45(as an active layer) is grown. Then, the magnesium-doped GaN layer 46(as a p-type cladding layer) is grown at a raised growing temperature,as shown in FIGS. 20A and 20B. The thickness of the InGaN layer 45 isabout 0.5 nm to about 3 nm. As with Examples 1 and 2 (mentioned above),there may be an instance where a quantum well layer (or a multiplequantum well layer) of (Al)GaN/InGaN, functioning as the active layer,is formed, or there may be another instance where a multilayer structureis formed with GaN or InGaN functioning as the guide layer. In such acase, it is desirable to grow the AlGaN layer directly on the InGaNlayer. The selective growth should preferably be carried out such thatthe window region 43 of the selective mask is filled with the entirecrystal layer extending in the lateral direction. Thus, it is possibleto produce the individual light-emitting devices in uniform sizes.

[0293] Subsequently, the masking layer is partly opened so that the GaNlayer 41 is exposed. In the removed part 47, the Ti/Al/Pt/Au electrode(as the n-electrode 48) is formed by vapor deposition. On the outermostsurface of the hexagonal pyramid, the Ni/Pt/Au or Ni(Pd)/Pt/Au electrode(as the p-electrode 49) is formed by vapor deposition (see FIGS. 21A and21B). These vapor depositions should be carried out accurately. Then,individual light-emitting devices are separated by RIE (reactive ionetching) or dicing, as shown in FIGS. 22A and 22B. Thus, thelight-emitting device in this example is completed.

[0294] The light-emitting device produced by the above-mentioned processhas a structure as shown in FIG. 23. It is composed mainly of thesapphire substrate 40 whose principal plane is the C⁺-plane and thesilicon-doped GaN layer 44 (as a crystal layer) which has grown on thesapphire substrate 40 with the silicon-doped GaN layer 41 (as a crystalseed layer) interposed between them. The silicon-doped GaN layer 44 hasa surface covered with the slant S-plane slanting to the principal planeof the substrate. The InGaN layer 45 (as an active layer) is parallel tothe S-plane. On the InGaN layer 45 is formed the magnesium-doped GaNlayer 46 as a cladding layer. The p-electrode 49 is formed on themagnesium-doped GaN layer 46. The n-electrode 48 is formed in the openregion 47 at the vicinity of the hexagonal pyramid, and it is connectedto the silicon-doped GaN layer 44 through the silicon-doped GaN layer41.

[0295] As with Examples 1 and 2 (mentioned above), the light-emittingdevice in this example (which is constructed as mentioned above) has anadvantage that, owing to the S-plane slanting to the principal plane ofthe substrate, the number of bonds from nitrogen atoms to gallium atomsincreases, which increases the effective V/III ratio. Therefore, theresulting light-emitting device has improved performance. In addition,the fact that the principal plane of the substrate is the C⁺-plane andhence, the S-plane is different from the principal plane of thesubstrate tends to decrease defects and dislocations extending from thesubstrate bend. Moreover, in this example, the selective growth islimited in the window region 43 and hence, it is easy to uniformlycontrol the size of the individual devices. The slant crystal planeslanting to the principal plane of the substrate prevents multiplereflection, thereby permitting the generated light to emergeefficiently.

Example 4

[0296] This example demonstrates a semiconductor light-emitting devicein which the crystal layer is grown in the shape of a hexagonal pyramidlarger than the window region or the selective mask. Its productionprocess and structure will be described with reference to FIGS. 24A to29.

[0297] On the sapphire substrate 50, whose principal plane is theC⁺-plane, is formed a low-temperature buffer layer in a manner similarto the examples mentioned above. Then, with the temperature raised toabout 1000° C., the silicon-doped GaN layer 51 is formed as the firstgrowing layer. On the entire surface of the silicon-doped GaN layer 51is formed the masking layer 52 (about 100 nm to about 500 nm thick) ofSiO₂ or SiN. In the masking layer 52 is formed a round opening (about 10μm in diameter) as the window region 53 by photolithography and etchingwith hydrofluoric acid based compound, as shown in FIGS. 24A and 24B.The direction of one side is perpendicular to (1-100). The size of theopening varies depending on the light-emitting device desired.

[0298] Then, the silicon-doped GaN layer 54 is grown again at a growingtemperature of about 1000° C. In the beginning, the silicon-doped GaNlayer 54 grows from the round window region 53. After growing for awhile, it takes the shape of a hexagonal pyramid surrounded by S-planesor (1-101) planes. It may take the shape of a hexagonal prismoid ifgrowing time is insufficient. After the silicon-doped GaN layer 54 hasgrown in the shape of a hexagonal pyramid, growing is continued foruntil the hexagonal pyramid becomes about 20 μm wide (with one sidebeing about 10 μm long). The height of the hexagonal pyramid is about1.6 times the side of the hexagonal pyramid. The resulting silicon-dopedGaN layer 54 is such that the base of the hexagonal pyramid extendsbeyond the window region 53 by about 16 μm, as shown in FIGS. 25A and25B. The width of about 20 μm of the hexagonal pyramid is merelyexemplary, and the width of about 10 μm may be acceptable.

[0299] The silicon-doped GaN layer is grown further. With the growingtemperature lowered, the InGaN layer 55 (as an active layer) is grown.Then, the magnesium-doped GaN layer 56 (as a p-type cladding layer) isgrown at a raised growing temperature, as shown in FIGS. 26A and 26B.The thickness of the InGaN layer 55 is about 0.5 nm to about 3 nm. Theremay be an instance where the active layer is a quantum well layer (or amultiple quantum well layer) of (Al)GaN/InGaN, or there may be anotherinstance where a multilayer structure is formed with GaN or InGaNfunctioning as the guide layer. In such a case, it is desirable to growthe AlGaN layer directly on the InGaN layer. In this stage the InGaNlayer 15 and the magnesium-doped GaN layer 56 extend over the maskinglayer 52 surrounding the window region 53, thereby entirely covering thesilicon-doped GaN layer 54 as the second grown layer. Thus, the InGaNlayer 55 (as an active layer) and the magnesium-doped GaN layer 56 haveno open ends (i.e., the ends are in direct contact with the maskinglayer 52). This prevents the active layer from oxidizing anddeteriorating.

[0300] Subsequently, the masking layer is partly opened so that the GaNlayer 51 is exposed. In the removed part 57, the Ti/Al/Pt/Au electrode(as the n-electrode 58) is formed by vapor deposition. On the outermostsurface of the hexagonal pyramid, the Ni/Pt/Au or Ni(Pd)/Pt/Au electrode(as the p-electrode 59) is formed by vapor deposition (see FIGS. 27A and27B). These vapor depositions should be carried out accurately. Then,individual light-emitting devices are separated by RIE (reactive ionetching) or dicing, as shown in FIGS. 28A and 28B. Thus, thelight-emitting device in this example is completed.

[0301] The light-emitting device produced by the above-mentioned processhas a structure as shown in FIG. 29. It is composed mainly of thesapphire substrate 50 whose principal plane is the C⁺-plane and thesilicon-doped GaN layer 54 (as the second grown layer) which has grownon the sapphire substrate 50 with the silicon-doped GaN layer 51 (as acrystal seed layer) interposed between them. The silicon-doped GaN layer54 has a surface covered with the slant S-plane slanting to theprincipal plane of the substrate. It also has a base whose area islarger than the window region 53.

[0302] This device has the InGaN layer 55 (as an active layer) which isparallel to the S-plane. On the InGaN layer 55 is formed themagnesium-doped GaN layer 56 as a cladding layer. The p-electrode 59 isformed on the magnesium-doped GaN layer 56. The n-electrode 58 is formedin the open region 57 at the vicinity of the hexagonal pyramid, and itis connected to the silicon-doped GaN layer 54 through the silicon-dopedGaN layer 51.

[0303] The semiconductor light-emitting device in this example, which isconstructed as mentioned above, is characterized by the silicon-dopedGaN layer 54, the InGaN layer 55, and the magnesium-doped GaN layer 56which extend entirely or partly onto the masking layer 52 surroundingthe window region 53. An advantage of this structure (with the maskremaining unremoved) is that the laterally grown part is held by asupport which does not disappear. Moreover, the masking layer 52remaining unremoved relieves steps due to the selectively grownstructure and also functions as a supporting layer for the first grownlayer 51 even when the substrate is stripped off by laser irradiation.This helps separate the n-electrode 58 and p-electrode 59 withcertainty, thereby preventing short-circuiting.

[0304] The structure of this device is characterized by thesilicon-doped GaN layer 54 which is entirely covered by the InGaN layer55 and the magnesium-doped GaN layer 56, so that the ends of the layers55 and 56 come into direct contact with the masking layer. In otherwords, they cover the active layer, with their ends being in directcontact with the masking layer 52. This produces the effect ofprotecting the active layer from oxidation and other deterioration whileincreasing the light emission area.

[0305] The light-emitting device in this example has an advantage that,owing to the S-plane slanting to the principal plane of the substrate,the number of bonds from nitrogen atoms to gallium atoms increases,which increases the effective V/III ratio. Therefore, the resultinglight-emitting device has improved performance. In addition, the factthat the principal plane of the substrate is the C⁺-plane and hence, theS-plane is different from the principal plane of the substrate tends todecrease defects and dislocations extending from the substrate bend. Theslant crystal plane slanting to the principal plane of the substrateprevents multiple reflection, thereby permitting the generated light toemerge efficiently. The active layer with a large area permits currentto be injected uniformly without current concentration and also permitsthe current density to be reduced.

Example 5

[0306] This example demonstrates a semiconductor light-emitting devicein which the p-electrode is not formed on the apex of a hexagonalpyramid of the crystal layer with S-planes which has grown larger thanthe selective mask. Its production process and structure will bedescribed with reference to FIGS. 30A to 32.

[0307] On the sapphire substrate 50, whose principal plane is theC⁺-plane, is formed a low-temperature buffer layer in a manner similarto the examples mentioned above, especially Example 4. Then, with thetemperature raised to about 1000° C., the silicon-doped GaN layer 51 isformed as the first growing layer. On the entire surface of thesilicon-doped GaN layer 51 is formed the masking layer 52 (about 100 nmto about 500 nm thick) of SiO₂ or SiN. In the masking layer 52 is formeda round opening (about 10 μm in diameter) as the window region byphotolithography and etching with hydrofluoric acid based compound. Thesize of the opening varies depending on the light-emitting devicedesired.

[0308] Then, the silicon-doped GaN layer 54 is grown again at a growingtemperature of about 1000° C. In the beginning, the silicon-doped GaNlayer 54 grows from the round window region 53. After growing for awhile, it takes the shape of a hexagonal pyramid surrounded by S-planesor (1-101) planes. It may take the shape of a hexagonal prismoid ifgrowing time is insufficient. After the silicon-doped GaN layer 54 hasgrown in the shape of a hexagonal pyramid, growing is continued untilthe hexagonal pyramid becomes about 20 μm wide (with one side beingabout 10 μm long). The height of the hexagonal pyramid is about 1.6times the side of the hexagonal pyramid. The resulting silicon-doped GaNlayer 54 is such that the base of the hexagonal pyramid extends beyondthe window region 53 by about 16 μm. The width of about 20 μm of thehexagonal pyramid is merely exemplary, and the width of about 10 μm maybe acceptable.

[0309] Silicon-doped GaN is grown further. With the growing temperaturelowered, the InGaN layer 55 (as an active layer) is grown. Then, themagnesium-doped GaN layer 56 (as a p-type cladding layer) is grown at araised growing temperature. The InGaN layer 55 and the magnesium-dopedGaN layer 56 are identical with those in Example 4. In this stage, theInGaN layer 55 and the magnesium-doped GaN layer 56 extend over themasking layer 52 surrounding the window region 53, thereby entirelycovering the silicon-doped GaN layer 54 as the second growing layer.Growing in this manner prevents the InGaN layer 55 (as an active layer)and the magnesium-doped GaN layer 56 from forming open ends, therebypreventing the active layer from deteriorating.

[0310] Subsequently, the masking layer is partly opened so that the GaNlayer 51 on the substrate 50 is exposed. In the removed part, theTi/Al/Pt/Au electrode (as the n-electrode 61) is formed by vapordeposition. On the outermost surface layer of the S-plane which hasgrown on the hexagonal pyramid, the Ni/Pt/Au or Ni(Pd)/Pt/Au electrode(as the p-electrode 62) is formed by vapor deposition (see FIGS. 30A and30B). The part at which the p-electrode 62 is formed is one which hassufficient steps found by observation with an AFM. In general, stepsfound by an AFM indicate that the crystal properties are comparativelypoor in the vicinity of the apex of the hexagonal pyramid. This is thereason why the p-electrode 62 is formed on the part excluding the apexand its vicinity. Vapor deposition to form the p-electrode 62 andn-electrode 61 should be carried out accurately so as to prevent themfrom coming into contact with the silicon-doped GaN layer 54 (as acrystal layer) and the silicon-doped GaN layer 51 (formed under themasking layer), thereby preventing short-circuiting. Then, individuallight-emitting devices are separated by RIE (reactive ion etching) ordicing (FIGS. 31A and 31B). Thus, the light-emitting device in thisexample is completed. A sectional view of the device is shown in FIG.32.

[0311] The light-emitting device constructed as mentioned above ischaracterized by the silicon-doped GaN layer 54, the InGaN layer 55, andthe magnesium-doped GaN layer 56 which entirely or partly extend overthe masking layer 52 surrounding the window region 53. An advantage ofthis structure (with the mask remaining unremoved) is that the laterallygrown part is held by a support which does not disappear. Moreover, themasking layer 52 remaining unremoved relieves steps due to theselectively grown structure and also separates the n-electrode 61 andp-electrode 62 with certainty, thereby preventing short-circuiting.

[0312] The structure of this device is also characterized by thesilicon-doped GaN layer 54 which is entirely covered by the InGaN layer55 and the magnesium-doped GaN layer 56, so that the ends of the layers55 and 56 come into direct contact with the masking layer. In otherwords, they cover the active layer, with their ends being in directcontact with the masking layer 52. This produces the effect ofprotecting the active layer from oxidation and other deterioration whileincreasing the light emission area.

[0313] Another advantage is that current injection into the active layertakes place such that the current density is lower in the vicinity ofthe apex than in the surrounding side faces, and that the part in whichcrystal properties are poor is excluded from the light-generating regionso as to improve the overall emission efficiency.

Example 6

[0314] This example demonstrates a semiconductor light-emitting devicewhich has the n-electrode formed on the reverse side of the substrate.Its production process and structure will be described with reference toFIGS. 33A to 39B.

[0315] On the sapphire substrate 50, whose principal plane is theC⁺-plane, a low-temperature buffer layer is formed in a manner similarto the examples mentioned above. Then, with the temperature raised toabout 1000° C., the silicon-doped GaN layer 51 is formed as the firstgrowing layer. On the entire surface of the silicon-doped GaN layer 51the masking layer 52 (about 100 nm to about 500 nm thick) of SiO₂ or SiNis formed. In the masking layer 52 a round opening (about 10 μm indiameter) is formed as the window region by photolithography and etchingwith hydrofluoric acid based compound. The direction of one side isperpendicular to (1-100). The size of the opening varies depending onthe light-emitting device desired.

[0316] Then, the silicon-doped GaN layer 54 is grown again at a growingtemperature of about 1000° C. In the beginning, the silicon-doped GaNlayer 54 grows from the round opening. After growing for a while, ittakes the shape of a hexagonal pyramid surrounded by S-planes or (1-101)planes. It may take the shape of a hexagonal prismoid if growing time isinsufficient. After the silicon-doped GaN layer 54 has grown in theshape of a hexagonal pyramid, growing is continued until the base of thehexagonal pyramid extends about 16 μm beyond the window region.

[0317] The silicon-doped GaN layer is grown further. With the growingtemperature lowered, the InGaN layer 55 (as an active layer) is grown.Then, the magnesium-doped GaN layer 56 (as a p-type cladding layer) isgrown at a raised growing temperature. The InGaN layer 55 and themagnesium-doped GaN layer 56 are identical to those described in Example4. In this stage, the InGaN layer 55 and the magnesium-doped GaN layer56 extend over the masking layer 52 surrounding the window region,thereby entirely covering the silicon-doped GaN layer 54 as the secondgrowing layer. Growing the layers in this manner prevents the InGaNlayer 55 (as an active layer) and the magnesium-doped GaN layer 56 fromforming open ends, thereby preventing the active layer fromdeteriorating.

[0318] As shown in FIGS. 33A and 33B, the p-electrode 71 is formed onthe outermost S-plane of the magnesium-doped GaN layer 56 before formingof an n-electrode. The separating grooves 72 reaching the principalplane of the sapphire substrate 50 are formed by RIE or dicing.Individual devices are separated from one another on the sapphiresubstrate 50 (see FIGS. 34A and 34B). The part constituting the deviceis separated from the sapphire substrate 50 by excimer laser. ResidualGa, for example, is removed by etching. On the reverse side of thedevice, the Ti/Al/Pt/Au electrode is formed by vapor deposition. Thiselectrode functions as the n-electrode 73, as shown in FIGS. 35A and35B.

[0319] FIGS. 36A-36C show another method of forming the n-electrode onthe reverse side. This method employs a second sapphire substrate 77,which is coated with an adhesive layer 78 and a resin layer 79. Thedevices shown in FIGS. 33A and 33B are embedded in the resin layer 79.Subsequently, the sapphire substrate 50 is removed by laser abrasion, asshown in FIG. 36A. An excimer laser (with a wavelength of about 248 nm)may be used for this purpose.

[0320] Residual Ga remaining on the surface is removed. On the surfacefrom which the sapphire substrate 50 has been removed is formed the maskM (such as a Ni mask), as shown in FIG. 36B. Individual devices areseparated from one another by RIE with a chlorine based gas or the like.The mask M is removed, and the electrode 76 of Ti/Pt/Au or Ti/Au isformed on the reverse side of the device.

[0321]FIG. 37 is a sectional view showing the completed semiconductorlight-emitting device. The n-electrode 73 should be arranged near thecomers so that it does not interrupt light. FIG. 38 shows the reverseside of the completed semiconductor light-emitting device. It should benoted that the n-electrode 74 has the hexagonal opening 75 whichcoincides with the hexagonal base of the silicon-doped GaN layer 54 asthe second growing layer, thereby permitting generated light to beextracted efficiently.

[0322] This example may be modified such that the n-electrode is atransparent electrode. FIGS. 39A and 39B show a light-emitting device inwhich the region corresponding to the device is removed from thesubstrate by using excimer laser, for example, and the transparentelectrode 76 is formed on the reverse side of the device. Additionally,the device has the same structure as shown in FIG. 37. Thus, the maskinglayer 52 remaining on the silicon-doped GaN layer 51 has the windowregion from which the hexagonal pyramid grows, which is composed of thesilicon-doped GaN layer 54, the InGaN layer 55, and the magnesium-dopedGaN layer 56, with the p-electrode 71 formed on the outermost layer. Thetransparent electrode 76 is formed from ITO (indium tin oxide) bylift-off technique on the reverse side of the silicon-doped GaN layer 51from which the substrate has been stripped off. Lift-off techniqueinvolves, for example, peeling away the unwanted metal and leavingbehind metal traces where desired.

[0323]FIG. 40 is a sectional view showing the completed semiconductorlight-emitting device having the transparent electrode 76. Thetransparent electrode 76 transmits light generated by the InGaN layer 55(as an active layer) which is held between the silicon-doped GaN layer54 and the magnesium-doped GaN layer 56. An advantage of this structure(with the masking layer 52 remaining) is that the laterally grown partis held by a support which does not disappear. Moreover, the maskinglayer 52 relieves steps due to the selectively grown structure and alsokeeps the p-electrode 71 and the transparent electrode 76 apart, therebypreventing short-circuiting, even when the substrate is stripped off bylaser irradiation, for example. In addition, the fact that lightgenerated by the active layer emerges through the transparent electrode76 makes it unnecessary for the optical path to circumvent theelectrode. Thus, another advantage is easy production and improved lightemergence efficiency (i.e., the structure that permits light to emergefrom the reverse side of the silicon-doped GaN layer 51 also permitslight to emerge, which has been reflected by the slant crystal planes).Since the p-electrode 71 is arranged near the apex of the hexagonalpyramid, it is possible to form the transparent electrode 76 over acomparatively large area on the reverse side of the silicon-doped GaNlayer 51, thereby reducing the contact resistance of the transparentelectrode 76 and obviating the necessity of fabricating the maskinglayer for the n-electrode lead. Therefore, the device in this examplecan be produced easily.

Example 7

[0324] This example demonstrates a semiconductor light-emitting devicewhich is produced by selective growth from an elongated window region.Its production process and structure is described with reference toFIGS. 41 to 44.

[0325] First, on the sapphire substrate 80, whose principal plane is theC⁺-plane, a buffer layer of AlN or GaN is formed at a low temperature ofabout 500° C., as shown in FIG. 41. Then, with the temperature raised toabout 1000° C., the silicon-doped GaN layer 81 is formed. On the entiresurface of the silicon GaN layer 81 the masking layer 82 (about 100 nmto about 500 nm thick) is formed of SiO₂ or SiN. In the masking layer82, the window region 83 (i.e., a rectangular opening measuring about 10μm×about 50 μm) is formed by photolithography and etching withhydrofluoric acid based compound. The long side of the opening alignswith the (1-100) direction. Then, with the temperature raised to about1000° C., crystal growing is carried out once again to form thesilicon-doped GaN layer 84. The silicon-doped GaN layer 84 grows in thewindow region 83 in the masking layer, but it takes a hexagonal shapesimilar to a ship's bottom after continued growing, as shown in FIG. 42.The surface of the hexagonal structure is covered with the S-plane.

[0326] When the top C-plane has become almost flat or has disappearedafter the lapse of sufficient time, the silicon-doped GaN layer is grownfurther. With the growing temperature lowered, the InGaN layer 85 (as anactive layer) is grown. Then, with the growing temperature raised again,the magnesium-doped GaN layer 86 (as a p-type cladding layer) is grown.The thickness of the InGaN layer 85 is about 0.5 nm to about 3 nm. As inExamples 1 and 2 (mentioned above), there may be an instance where aquantum well layer (or a multiple quantum well layer) of (Al)GaN/InGaN,functioning as the active layer, is formed, or there may be anotherinstance where a multilayer structure is formed with GaN or InGaNfunctioning as the guide layer. In such a case, it is desirable to growthe AlGaN layer directly on the InGaN layer.

[0327] Subsequently, the masking layer is partly opened so that the GaNlayer 81 is exposed. In the removed part, the n-electrode 87 ofTi/Al/Pt/Au is formed by vapor deposition. On the outermost surface ofthe previously grown layers, the p-electrode 88 of Ni/Pt/Au orNi(Pd)/Pt/Au by vapor deposition (FIG. 43). These vapor depositionsshould be carried out accurately. Subsequently, individuallight-emitting devices are separated by RIE (reactive ion etching) ordicing. Thus, the light-emitting device in this example is completed.

[0328] The light-emitting device produced by the above-mentioned processhas a structure as shown in FIG. 44. It is characterized by thesilicon-doped GaN layer 84 which possesses the S-plane as well as the(11-22) plane, thereby permitting the active region to be formed over alarge area. The effect of this structure is uniform current flow withoutcurrent concentration and reduced current density.

Example 8

[0329] This example demonstrates a semiconductor light-emitting devicein which the crystal layer is a hexagonal prismoid larger than theselective mask or window region. Its production process and structurewill be described with reference to FIGS. 45A to 50.

[0330] First, on the sapphire substrate 90, whose principal plane is theC⁺-plane, a low-temperature buffer layer is formed in a manner similarto the examples mentioned above. Then, with the temperature raised toabout 1000° C., the silicon-doped GaN layer 91 is formed. On the entiresurface of the silicon-doped GaN layer 91, the masking layer 92 (about100 nm to about 500 nm thick) is formed of SiO₂ or SiN. In the maskinglayer 92, the window region 93 (or a round opening about 10 μm indiameter) is formed by photolithography and etching with hydrofluoricacid based compound, as shown in FIGS. 45A to 45B. The size of theopening varies depending on the light-emitting device desired.

[0331] Then, with the temperature raised to about 1000° C., crystalgrowing is carried out once again to form the silicon-doped GaN layer94. The silicon-doped GaN layer 94 grows in the window region 93, but ittakes the shape of a hexagonal prismoid, whose side plane is the S-plane(1-101) and whose top plane is the C-plane parallel to the principalplane of the substrate, after continued growing. Crystal growing iscarried out for a sufficient length of time so that the silicon-dopedGaN layer 94 takes the shape of a hexagonal prismoid whose top C-planeis flat (see FIGS. 46A to 46B). This prismoid forms in a shorter timethan the above-mentioned hexagonal pyramid.

[0332] The growing of the silicon-doped GaN is continued. With thegrowing temperature lowered, the InGaN layer 95 (as an active layer) isgrown. Then, with the growing temperature raised again, themagnesium-doped GaN layer 96 (as a p-type cladding layer) is grown, asshown in FIGS. 47A to 47B. The thickness of the InGaN layer 95 is about0.5 nm to about 3 nm. As with the examples, mentioned above, there maybe an instance where a quantum well layer or a multiple quantum welllayer is formed, or where a guide layer is formed.

[0333] Subsequently, the masking layer is partly opened so that the GaNlayer 91 is exposed. In the removed part 97, the n-electrode 98 ofTi/Al/Pt/Au is formed by vapor deposition. On the outermost surface ofthe previously grown pyramid, the p-electrode 99 of Ni/Pt/Au orNi(Pd)/Pt/Au is formed by vapor deposition (see FIGS. 48A to 48B). Asmentioned above, these vapor depositions should be carried outaccurately. Then, individual light-emitting devices are separated by RIE(reactive ion etching) or dicing, as shown in FIGS. 49A to 49B. Thus,the light-emitting device in this example is completed.

[0334] The light-emitting device produced by the above-mentioned processhas a structure as shown in FIG. 50. It is characterized by the sapphiresubstrate 90 which has the C⁺-plane as its principal plane and thesilicon-doped GaN layer 94 formed thereon which takes the shape of ahexagonal prismoid with a flat top. The hexagonal prismoid lacks theapex part in which the crystal properties are poor. Therefore, thisstructure prevents loss in light emission characteristics. Moreover, thefact that the hexagonal prismoid is formed in a comparatively short timeis also desirable for the process.

[0335] The structure, having all or part of the silicon-doped GaN layer94, the InGaN layer 95, and the magnesium-doped GaN layer 96 extendingover the masking layer 92 around the window region 93, with the maskremaining unremoved, relieves steps due to the selective growth andseparates the n-electrode 98 and p-electrode 99 with certainty, therebypreventing short-circuiting. An alternative structure is possible inwhich the ends of the InGaN layer 35 and the magnesium-doped GaN layer36 are in direct contact with the masking layer 92. Consequently, allthe ends come into direct contact with the masking layer 32, therebycovering the active layer, thereby protecting the active layer fromoxidation and other deterioration while also increasing the lightemission area.

[0336]FIGS. 51 and 52 show another structure of the semiconductorlight-emitting device of hexagonal prismoid structure. FIGS. 51A to 51Bis a diagram showing the process of forming the electrode of the device.The semiconductor light-emitting device shown in FIGS. 51 and 52 is amodified example of the semiconductor light-emitting device shown inFIG. 50. It is characterized by the sapphire substrate 90 which isremoved by irradiation with excimer laser and the n-electrode 98 b whichis formed on the reverse side of the silicon-doped GaN layer 91. On thegrown layer, in the shape of hexagonal prismoid with a flat top are thesilicon-doped GaN layer 94, the InGaN layer 95, and the magnesium-dopedGaN layer 96 which entirely or partly extend to the masking layer 92around the window region. On the outermost layer of them, thep-electrode 99 is formed.

[0337] The structure shown in FIGS. 51A, 51B and 52 is characterized bythe n-electrode 98 b which is formed on the reverse side of thesilicon-doped GaN layer 91 outside the window region in the maskinglayer 92 through which light emerges. An advantage of this structure isthat the size of the semiconductor light-emitting device is reduced andit is not necessary to form the contact region by opening the maskinglayer 92. This is convenient to production and size reduction. Also inthe semiconductor light-emitting device of a hexagonal prismoidstructure, the n-electrode 98 b may be replaced by a transparentelectrode of ITO film, thereby increasing the contact area andsimplifying the manufacturing process.

Example 9

[0338] This example demonstrates a semiconductor light-emitting devicein which the p-electrode is formed such that the surface of thesubstrate occupies a large area. Its production process and structurewill be described with reference to FIGS. 53A and 53B.

[0339] The process in this example is the same as that described inExample 6 up to the stage in which the magnesium-doped GaN layer 56 isgrown. Therefore, the parts involved up to this stage are given the samereference numerals but their explanation is omitted.

[0340] An opening is made in the masking layer 52 on the sapphiresubstrate 50. This opening is close to one side of the substrate 50. Inthis opening, the n-electrode 100 of Ti/Al/Pt/Au is formed by vapordeposition. This n-electrode 100 supplies current to the region composedof a plurality of hexagonal pyramids. The p-electrode 101 of Ni/Pt/Au orNi(Pd)/Pt/Au is formed by vapor deposition. The p-electrode 101,covering a large area, permits each device to emit strong light. Thesedevices function as a lighting system if they are given the samepotential, or these devices function as an image display unit if thep-electrodes 101 are given independent signals. Moreover, these devicesconstitute a multicolor or full-color image display unit if they are soarranged as to correspond to the three primary colors. The image displayunit or lighting system may be constructed of the above-mentioneddevices only or a mixture of the above-mentioned devices and otherdevices produced in different ways.

[0341] All or part of the silicon-doped GaN layer 54, the InGaN layer55, and the magnesium-doped GaN layer 56 extend to the masking layer 52around the window region 53. The mask remaining unremoved relieves stepsdue to the selective growth and also separates the n-electrode 100 andp-electrode 101 from each other with certainty, thereby preventingshort-circuiting. Another structure is also possible in which the InGaNlayer 55 and the magnesium-doped GaN layer 56 come into direct contactwith the masking layer 52. The advantage of this structure is that thelayers' ends in direct contact with the masking layer 52 cover theactive layer, thereby protecting the active layer from oxidation andother deterioration. Another advantage is an increased light emissionarea.

Example 10

[0342] This example demonstrates an image display unit or a lightingsystem constructed of the semiconductor light-emitting devices obtainedin the above-mentioned examples which are so arranged as to suit asimple matrix drive, as shown in FIG. 54. Each semiconductorlight-emitting device is arranged, on the substrate 120, in such amanner that its region emitting red color, its region emitting bluecolor, and its region emitting green color are provided linearly. Theyare supplied with current through respective wires 126R, 126G, and 126Bwhich are connected to the respective p-electrodes 124. The n-electrode122 is a common electrode. If necessary, selective transistors may beformed to control pixels individually. The masking layer 125 remains onthe substrate 120, so that it relieves steps on its underlyingsilicon-doped GaN layer 121.

[0343] The semiconductor light-emitting devices in each row for redcolor, blue color, and green color have active layers which are capableof emitting light with a first, second, and third wavelength,respectively. The devices will function as an image display unit fortwo-dimensional images if the wires 126R, 126G, and 126B are givensignals independently. The devices will function as a lighting system ifthe wires 126R, 126G, and 126B are given identical signals.

[0344] Additionally, the process in the foregoing examples consists offorming a low-temperature buffer layer on the sapphire substrate,growing the GaN layer, forming the selective mask, and performingselective growth. The process may be so modified as to form the GaNlayer directly on Si at about 900° C., or to form an AlN layer (5 nmthick) on Si at about 1000° C. and then grow GaN, or to use the GaNsubstrate and subsequently form the selective mask.

Example 11

[0345] This example demonstrates a semiconductor light-emitting devicewhich has on a substrate for growth 131, with the C-plane (i.e. the(0001) plane), (for example, a sapphire substrate), an n-type GaN layer132 (as an underlying layer for growth) grown by MOCVD, MOVPE or thelike and a masking layer 133 (as a growth inhibiting film of siliconoxide, silicon nitride, or tungsten).

[0346] In the masking layer 133, a window region 134 which has ahexagonal opening is formed. In the window region 134, the crystal grownlayer 135 (having a triangular cross section) is formed by selectivegrowth. The crystal grown layer 135 is an n-type GaN layer or an AlGaNlayer, for example, and has a cross section of an approximately regulartriangle. It is hexagonal when viewed from above, and it takes the shapeof a hexagonal pyramid as a whole.

[0347] The crystal grown layer 135 has side faces (which are the S-planeor an equivalent thereof) slanting to the principal plane of thesubstrate. On the crystal grown layer 135 is an n-type cladding layerwith a controlled concentration, for example. On the n-type claddinglayer are formed the active layer 136 and the second conductive layer137 (which functions as a p-type cladding layer). The active layer 136and the second conductive layer 137 are formed to cover the S-plane ofthe crystal grown layer 135. The active layer 136 is grown along theS-plane of the crystal grown layer 135, and it is not parallel to theprincipal plane of the substrate 131. The second conductive layer 137 isa p-type GaN layer or an AlGaN layer. An AlGaN layer may be formed onthe active layer 136.

[0348] On the second conductive layer 137, the second electrode 139(which functions as a p-electrode) is formed in the form of multi-layermetal film of Ni/Pt/Au or Ni(Pd)/Pt/Au. In the opening in the maskinglayer 133, the first electrode 138 (which functions as an n-electrode)is formed in the form of a multi-layer metal film of Ti/Al/Pt/Au, forexample. The first electrode 138 and the second electrode 139 may beformed by vapor deposition, lift-off technique, or the like.

[0349] An advantage of the semiconductor light-emitting device in thisexample is that the active layer 136 has a large area functioning torelieve the current density injected into the active layer 136. Inparticular, the area S of the active layer 6 is sufficiently largebecause the active layer 136 extends along the S-plane of the crystalgrown layer 135, not parallel to the principal plane of the substratefor growth 131. The area S of the active layer 6 may be larger than thesum of S1 and S2, where S2 is the area of the first electrode 138 and S1is the area of the crystal grown layer 135 projected to the principalplane of the substrate, as shown in FIG. 55.

[0350] In the case where the device in this example is a light-emittingdiode having the size of, for example, a 30 μm square, the area of S2 isabout 20 μm×about 5 μm or about 100 μm² and the area of S1 is about 20μm×about 20 μm or about 400 μm² at the largest. S2 is the region inwhich the first electrode comes into contact with the underlyingconductive layer as the first conductive layer, and S1 is the projectedregion of the active layer. Therefore, by making the total area of theactive layer equal to or larger than about 500 μm² (i.e., S1+S2), it ispossible to obtain the device structure according to the presentinvention.

[0351] Conversely, where the crystal grown layer 135 formed by selectivegrowth is a quadrangular pyramid whose base is about a 20 μm square andwhose side faces are formed at an angle of 45°, the total area of theactive layer 136 which is uniformly formed on the side faces is about 20μm×about 20 μm/cos 45° or about 566 μm² (i.e., clearly bigger than about500 μm²). The area S of the active layer increases even more when it isformed on the S-plane of a hexagonal pyramid (with an angle of about62°).

[0352]FIGS. 56 and 57 show that when the area S of the active layer 136is increased to relieve the brightness saturation, it becomes largerthan the area W1 of the window region 133 (see FIG. 56) or the area W2of the crystal grown layer projected to the principal plane of thesubstrate in its normal direction (see FIG. 57). When the active layer136 extends along the S-plane of the crystal grown layer 135, notparallel to the principal plane of the substrate 131, the area S of theactive layer 136 becomes larger than the area W1 or the projected areaW2. In other words, the active layer 136 has a sufficient area, therebyeffectively relieving brightness saturation and improving devicereliability.

[0353] The light-emitting device constructed as shown in FIG. 55 offersan advantage that, in addition to the effect produced by the increasedarea of the active layer, the S-plane slanting to the principal plane ofthe substrate increases the number of bonds from nitrogen atoms togallium atoms, thereby increasing the effective V/III ratio. Therefore,the resulting light-emitting device has improved performance. Inaddition, dislocations extending from the substrate bend and defectstend to decrease. The slant crystal plane slanting to the principalplane of the substrate prevents multiple reflection, thereby permittingthe generated light to emerge efficiently. The structure in which theactive layers 136 are isolated from one another obviates the necessityof etching the active layer 136, thereby eliminating damage to theactive layers. Another advantage is that the effective area of theactive layer 136 is not reduced by the electrode.

Example 12

[0354] This example demonstrates a semiconductor light-emitting devicein which the crystal grown layer 154 is formed in a stripe pattern onthe substrate 150, as shown in FIG. 58. The semiconductor light-emittingdevice consists of the substrate for growth 150, the underlying layerfor growth 151, the masking layer 152, and the crystal grown layer 154in a stripe pattern which is formed in the window region in the maskinglayer 152. The crystal grown layer 154 has the side face 156 which isthe S-plane. The active layer 155 is extendingly formed also on theslant side face 156, so that the area of the active layer 155 is largerthan the projected area of the crystal grown layer 154, therebyeffectively relieving brightness saturation and improving devicereliability.

Example 13

[0355] This example demonstrates a semiconductor light-emitting devicein which the crystal grown layer 164 is formed in the shape of anelongated quadrangular prismoid on the substrate 160, as shown in FIG.59. The semiconductor light-emitting device consists of the substratefor growth 160, the underlying layer for growth 161, the masking layer162, and the crystal grown layer 164 formed in the shape of a stripe andan elongated quadrangular prismoid in the window region in the maskinglayer 162. The crystal grown layer 164 has the side face 163S which isthe S-plane. The face 164 at the end in the lengthwise direction is the(11-22) plane. The top face 163C of the crystal grown layer 164 is theC-plane which is identical with the principal plane of the substrate.The active layer, which is not shown, extends over the slant side face163S, the face 164, and the top face 163C, so that the area of theactive layer is larger than the projected area of the crystal grownlayer 164, thereby effectively relieving brightness saturation andimproving device reliability.

Example 14

[0356] This example demonstrates a semiconductor light-emitting devicein which the crystal grown layer 174 is formed in the shape of aquadrangular trapezoid on the substrate for growth 170, as shown in FIG.60. The semiconductor light-emitting device consists of the substratefor growth 170, the underlying layer for growth 171, the masking layer172, and the crystal grown layer 173 which is formed in the shape of aquadrangular prismoid in the window region in the masking layer 172. Thequadrangular prismoids are arranged in a matrix pattern. The crystalgrown layer 173 has the slant side face 173S which is the S-plane andthe other side face 174 which is the (11-22) plane. The top plane 173Cof the crystal grown layer 173 is the C-plane which is identical (i.e.parallel) to the principal plane of the substrate. The active layer,which is not shown, extends over the slant side face 173S, the face 174,and the top face 173C, so that the area of the active layer is largerthan the projected area of the crystal grown layer 173, therebyeffectively relieving brightness saturation and improving devicereliability.

Example 15

[0357] This example demonstrates a semiconductor light-emitting devicein which the crystal grown layer 183 is formed in the shape of ahexagonal pyramid on the substrate for growth 180, as shown in FIG. 61.The semiconductor light-emitting device consists of the substrate forgrowth 180, the underlying layer for growth 181, the masking layer 182,and the crystal grown layer 183 which is formed in the shape of ahexagonal pyramid in the window region in the masking layer 182. Thehexagonal pyramids are arranged in a matrix pattern. The crystal grownlayer 183 has the slant side face which is the S-plane. The activelayer, which is not shown, extends over the slant S-plane, so that thearea of the active layer is larger than the projected area of thecrystal grown layer 183. Refer to FIG. 55 and Example 11, for example,for a discussion regarding the relationship of the area of the activelayer and the projected area of the crystal grown layer. This structureeffectively relieves brightness saturation and improves devicereliability.

Example 16

[0358] This example demonstrates a semiconductor light-emitting devicein which the crystal grown layer 193 is formed in the shape of ahexagonal prismoid is formed on the substrate for growth 190, as shownin FIG. 62. The semiconductor light-emitting device consists of thesubstrate for growth 190, the underlying layer for growth 191, themasking layer 192, and the crystal grown layer 193 which is formed inthe shape of a hexagonal prismoid in the window region in the maskinglayer 192. The hexagonal prismoids are arranged in a matrix pattern. Thecrystal grown layer 193 has the slant side face 193S which is theS-plane, and also has the top face 193C which is the C-plane identicalto the principal plane of the substrate. The base of the hexagonalpyramid is the M-plane or the (1-100) plane at the low position (i.e.the crystal grown layer having the S-plane as a side face bends toencompass the M-plane at the base of the hexagonal pyramid). The activelayer, which is not shown, extends over the slant S-plane and theC-plane, so that the area of the active layer is larger than theprojected area of the crystal grown layer 193. This structureeffectively relieves brightness saturation and improves devicereliability.

Example 17

[0359] This example demonstrates the process for producing thesemiconductor light-emitting device shown in FIG. 55. The process isdescribed with reference to FIGS. 63 to 68.

[0360] On the substrate for growth 200 (for example, a sapphiresubstrate) the n-type GaN layer 201 (as an underlying layer for growth)is formed by MOCVD or the like, as shown in FIG. 63. The n-type GaNlayer 201 needs not be n-type initially. However, it is acceptable solong as its uppermost face is n-type. The desired n-type GaN layer 201may be formed by doping with silicon, for instance.

[0361] On the entire surface of the n-type GaN layer 201 the maskinglayer 202 is formed by CVD or the like, as shown in FIG. 64. The maskinglayer 202 is a silicon oxide film, silicon nitride film, tungsten film,or the like which functions as a growth inhibiting film. The maskinglayer 202 is partly removed to form a plurality of hexagonal windowregions 203 corresponding to the regions in which the devices areformed.

[0362] Selective growth is carried out so as to form the n-type (Al)GaNlayer 204 as the crystal grown layer in the window region 203, as shownin FIG. 65. This n-type (Al)GaN layer 204 also functions as a claddinglayer, and it takes the shape of an approximately hexagonal pyramid. Theslant side face is the S-plane.

[0363] On the slant side face are formed the InGaN layer 205 (as anactive layer) and the p-type (Al)GaN layer 206, as shown in FIG. 66. TheInGaN layer 205 as an active layer extends broadly over the S-plane ofthe (Al)GaN layer 204 as the crystal grown layer, not parallel to theprincipal plane of the substrate for growth. The area S of the activelayer is larger than the area of the window region 203 and the projectedarea of the crystal grown layer. It is possible to form an AlGaN layeron the InGaN layer 205.

[0364] When poly-GaN or the like is grown on the masking layer,unnecessary parts are removed by etching. The masking layer 202 isremoved partly or entirely to form the n-side contact region 207, asshown in FIG. 67. The p-electrode 209 of Ni/Pt/Au or Ni(Pd)/Pt/Au isformed by vapor deposition or the like. The n-electrode 78 ofTi/Al/Pt/Au is formed in the contact region 207 by lift-off technique orthe like (see FIG. 68). After alloying, the device on the substrate iscompleted.

[0365] The basic structures of the individual devices are so small thatit is difficult to separate them from one another. However, it is onlynecessary to separate them into groups by dicing, cleavage and the like,each group consisting of devices arranged in one dimension or twodimensions. The internal basic structures of individual devices in eachgroup may or may not be driven independently. The GaN crystals grown onthe sapphire substrate can be peeled off from the sapphire substrate ifthe sapphire/GaN interface is subjected to UV laser abrasion through thesapphire, as reported by W. S. Wong et al. in APL-75-10, 1360-2. If thefirst grown film (the first conductive film) is removed by etchingbefore or after laser abrasion, it is possible to form a singlesemiconductor light-emitting device having the basic structure accordingto an embodiment of the present invention.

[0366] As mentioned above, the process in this example offers theadvantage that the S-plane can be formed easily by selective growth andthe active layer can be formed on the crystal grown layer whose sideface is the S-plane, thereby obtaining the active layer with a largearea.

Example 18

[0367] This example demonstrates a semiconductor light-emitting devicehaving the structure as shown in FIG. 69. The device includes thesubstrate for growth 210, the second grown layer 211, the firstconductive layer 211 (covering the second grown layer 211), the activelayer 213, and the second conductive layer 219. Although there is not amasking layer or window regions, the area of the active layer 213 ismade larger, by selective growth, than the projected area of the crystalgrown layer, thereby effectively relieving brightness saturation andimproving device reliability. In other words, even in the case where agrowth inhibiting film (such as a masking layer) is not used, it ispossible to form a stable plane and produce the same effect as thatwhich would be obtained by forming a growth inhibiting film, ifmicrofabrication is carried out by etching (for example, surfaceirregularities are formed on the substrate for growth or the crystalfilm which has been grown previously).

[0368] Additionally, according to an embodiment of the presentinvention, a hexagonal opening is most desirable as the window region inwhich the hexagonal pyramid is grown. However, the shape of the openingor the direction of the boundary of the opening is arbitrary because thestable plane is eventually formed by itself even in the case of a roundopening. The present invention is applicable also to the structure inwhich the stable plane, such as the (11-22) plane and the (1-100) planeother than the (1-101) plane in a wurtzite crystal, is formed by itself.

[0369] At present, red LEDs are usually made from an AlGaInP compound ofzincblende structure. This compound has stable planes such as the (011)plane, the (111) plane, and the (11-1) plane with respect to the (001)substrate. If it is grown under adequate conditions, it is possible toform the stable plane and the active layer thereon.

Example 19

[0370] This example demonstrates a semiconductor light-emitting deviceas shown in FIG. 70, which is formed in the following manner. Onsubstrate for growth 221 such as a sapphire substrate with the C-plane(i.e. the (0001) plane) the underlying layer 222 (which is an n-type GaNlayer) is formed by MOCVD, MOVPE or the like.

[0371] On the underlying layer for growth 222, the masking layer 223 isformed as a growth inhibiting film, for example, a silicon oxide film, asilicon nitride film, a tungsten film, the line and combination thereof.In the masking layer 223, the window region 224 is formed as a hexagonalopening. In this window region 224, the crystal grown layer 225 isformed by selective growth, thereby obtaining a shape with a triangularcross section. This crystal grown layer 225 is an n-type GaN layer orAlGaN layer and has a cross section of an approximately regulartriangle. It is hexagonal when viewed from above and it takes the shapeof a hexagonal pyramid as a whole.

[0372] The crystal grown layer 225 has the crystal plane (or the S-planeor a plane equivalent thereto) slanting to the principal plane of thesubstrate. On the crystal grown layer 225, an n-type cladding layer isformed by adjusting the concentration of the outermost portion of thecrystal grown layer 225. On the n-type cladding layer are formed theactive layer 226 and the second conductive layer 227 (which functions asa p-type cladding layer). The active layer 226 and the second conductivelayer 227 (which functions as a p-type cladding layer) are so formed asto cover the S-plane of the crystal grown layer 225. The active layer226 is grown along the S-plane of the crystal grown layer 225 and it isnot parallel to the principal plane of the substrate for growth 221. Thesecond conductive layer 227 is a p-type GaN layer or an AlGaN layer. AnAlGaN gap layer may be formed on the active layer 226. In this example,the surface of the second conductive layer 227 becomes the interfacewith the second electrode to be formed subsequently, and this interfacefunctions as the reflecting plane 240 for light generated by the activelayer 226.

[0373] On the second conductive layer 227, the second electrode (notshown in FIG. 70, which functions as a p-electrode), is formed in theform of a multi-layer metal film of Ni/Pt/Au. In the opening in themasking layer, the first electrode, which functions as an n-electrode,is formed in the form of a multi-layer metal film of Ti/Al/Pt/Au. Thefirst and second electrodes may be formed by vapor deposition, lift-offtechnique or the like.

[0374] The semiconductor light-emitting device in this example ischaracterized by enabling part of the light generated within to emergeafter reflection by the reflecting plane 240 which is parallel to theslant crystal plane. Since reflection improves the light emergenceefficiency, the semiconductor light-emitting device has increasedbrightness. Moreover, the reflecting plane 240 is formed on the slantcrystal plane which can be readily formed by itself by selective growthwithout additional etching.

[0375]FIG. 71 is a sectional view showing major parts of thesemiconductor light-emitting device. The device has its substrate forgrowth removed by irradiation with excimer laser through the reverseside, so that the bottom of the underlying layer for growth 222functions as the light emerging window 228. The underlying layer forgrowth 222 is a silicon-doped GaN layer, which is connected to ann-electrode (not shown). As shown in FIG. 70, the light generated by theactive layer 226 advances to the second conductive layer 227 to bereflected by the reflecting plane 240, and it eventually emerges fromthe light emerging window 228. The light generated by the active layer226 also advances to the light emerging window 228. Thus, the lightundergoes total reflection and is directed to the reflecting plane 240.The reflected light advances along the optical path altered on the basisof a relationship of a reflection angle to an incident angle, andemerges from the light emerging window 228 if the angle of incidence issmaller than the critical angle.

[0376] The mechanism of reflection will be explained in more detailbelow. The refractive index in the device is larger than that in theoutside. Therefore, light with a large incident angle to the interfaceexperiences total reflection. The condition of total reflection is asfollows.

φc=sin⁻¹(n ₁ /n ₂)

[0377] (where, (φc denotes the critical incident angle to the interface,and n₁ and n₂ respectively denote the refractive index of the outsideand the inside: For example, (φc is 24.6° when n₁ is equal to 1 and n₂is equal to 2.4.

[0378] With the semiconductor light-emitting device constructed as shownin FIG. 1, a portion of the light generated by the active layerexperiences total reflection by the window region and that portion oflight experiences total reflection repeatedly, without emerging from thewindow. This does not occur in a semiconductor device made pursuant toan embodiment of the present invention because the reflecting plane 240is inclined so that that a portion of the light which has experiencedtotal reflection is reflected again by the reflecting plane and returnedalong the different optical path not involved with total reflection.Thus, the light emerges from the window, therefore improving lightemergence efficiency and increasing brightness. Consequently, thesemiconductor light-emitting device in this example has improved lightemergence efficiency and high brightness.

[0379] FIGS. 72 to 76 illustrate the results of simulation of thereflecting plane. FIG. 72 is a perspective view showing the model of thecrystal grown layer which was used as the base of calculations. FIG. 73is a diagram showing the model which was used to calculate the angledependence. FIG. 74 is a diagram showing the dependence of angle onlight emergence efficiency. FIG. 75 is a diagram showing the model whichwas used to calculate the height dependency. FIG. 76 is a diagramshowing the dependence of height on light emergence efficiency.

[0380] The simulation is based on the assumption that the crystal grownlayer has the flat C-plane at its top and also has the active layerwhich is not parallel to the principal plane of the substrate forgrowth. This assumption does not differ essentially from the actual onein light emergence efficiency. The angle dependence was simulated on thefollowing assumption, as shown in FIG. 73. The sapphire substrate has arefractive index of n equal to 1.65. The active layer is 20 μm wide andis formed 5 μm above the substrate. The crystal grown layer has arefractive index of n equal to 2.4. The reflecting plane has areflectivity of 70% and is formed at a height of 10 μm. On the basis ofthis assumption, the angle of reflection by the reflecting plane wascalculated. The results are shown in FIG. 74. It is noted thatimprovement in light emergence efficiency is achieved in the range ofabout 50° to about 90°, with better results near about 50°.

[0381] The height dependence was simulated on the following assumption,as shown in FIG. 75. The sapphire substrate has a refractive index of nequal to 1.65. The active layer is 20 μm wide and is formed d/2 μm abovethe substrate. The crystal grown layer has a refractive index of n equalto 2.4. The reflecting plane has a reflectivity of 70%. The reflectingplane (S-plane) is formed at an angle of 62°. The results are shown inFIG. 76. It is noted that light emergence efficiency is improved as theheight d increases. The results of the simulations shown in FIGS. 74 and76 suggest that light emergence efficiency is improved as the angle θ ofthe side face is decreased and as the aspect ratio (the ratio of heightd to the width of the device) is increased. In other words, the smallerthe device size, the shorter the time required for crystal growth, andthe smaller the device size, the more significant the effect.

[0382] The semiconductor light-emitting device in this example ischaracterized in that part of light generated in it emerges afterreflection by the reflecting plane 240 which is parallel to the slantcrystal plane. Since reflection by the reflecting plane 240 improves theemergence efficiency, the semiconductor light-emitting device hasincreased brightness. Moreover, the reflecting plane 240 is formed onthe slant crystal plane which can be readily formed by itself byselective growth without additional etching.

[0383] The light-emitting device constructed as shown in FIG. 70 offersan advantage that, in addition to the effect produced by the increasedarea of the active layer, the S-plane slanting to the principal plane ofthe substrate increases the number of bonds from nitrogen atoms togallium atoms, thereby increasing the effective V/III ratio. Therefore,the resulting light-emitting device has improved performance. Inaddition, it is believe that dislocations extending from the substratecan bend thereby decreasing defects. The slant crystal plane slanting tothe principal plane of the substrate prevents multiple reflection,thereby permitting the generated light to emerge efficiently. Thestructure in which the active layers 226 are isolated or separated fromone another which obviates the necessity of etching the active layer226, thereby eliminating damages to the active layer. Another advantageis that the effective area of the active layer 226 is not reduced by theelectrode.

Example 20

[0384] This example demonstrates a semiconductor light-emitting devicein which the crystal grown layer 254 on the substrate for growth 250takes the shape of a stripe, as shown in FIG. 77. The device includesthe substrate for growth 250, the underlying layer for growth 251, themasking layer 252, and the crystal grown layer 254 formed in the windowregion in the masking layer 252. The crystal grown layer 254 has theslant side face 256 as the S-plane, on which the active layer 255 isformed. The light generated by the device is reflected by the reflectingplane parallel to the S-plane, which improves light emergenceefficiency. Therefore, the semiconductor light-emitting device has highbrightness and the slant crystal grown layer as the base of thereflecting plane is readily formed by selective growth. Thus, the deviceeffectively relieves brightness saturation and improves devicereliability.

Example 21

[0385] This example demonstrates a semiconductor light-emitting devicein which the crystal grown layer 264 on the substrate for growth 260takes the shape of an elongated prismoid, as shown in FIG. 78. Thedevice includes the substrate for growth 260, the underlying layer forgrowth 261, the masking layer 262, and the crystal grown layer 264formed in the window region in the masking layer 262. The crystal grownlayer 264 has the slant side face 263S as the S-plane, the longitudinalend face 264 as the (11-22) plane, and the top face 263C as the C-plane(which is identical to the principal plane of the substrate). The activelayer (which is not shown) is formed on the slant side face 263S, theend face 264, and the top face 263C. The light generated by the deviceis reflected by the reflecting plane parallel to the S-plane, whichimproves light emergence efficiency. Therefore, the semiconductorlight-emitting device has high brightness and the slant crystal grownlayer as the base of the reflecting plane is readily formed by selectivegrowth. Thus, the device effectively relieves brightness saturation andimproves device reliability.

Example 22

[0386] This example demonstrates a semiconductor light-emitting devicein which the crystal grown layer 274 on the substrate for growth 270takes the shape of a quadrangular prismoid, as shown in FIG. 79. Thedevice includes the substrate for growth 270, the underlying layer forgrowth 271 formed thereon, the masking layer 272, and the crystal grownlayer 273 formed in the window region in the masking layer 272. Thequadrangular prismoids are arranged in a matrix. The crystal grown layer273 (in the shape of a quadrangular prismoid) has the slant side face273S as the S-plane, another slant side face 274 as the (11-22) plane,and the top face 2753C as the C-plane (which is identical to theprincipal plane of the substrate). The active layer (which is not shown)is formed on the slant side face 273S, another face 274, and the topface 273C. The light generated by the device is reflected by thereflecting plane parallel to the S-plane, which improves light emergenceefficiency. Therefore, the semiconductor light-emitting device has highbrightness and the slant crystal grown layer as the base of thereflecting plane is readily formed by selective growth. Thus, the deviceeffectively relieves brightness saturation and improves devicereliability.

Example 23

[0387] This example demonstrates a semiconductor light-emitting devicein which the crystal grown layer 283 on the substrate for growth 280takes the shape of a hexagonal pyramid, as shown in FIG. 80. The deviceincludes the substrate for growth 280, the underlying layer for growth281 formed thereon, the masking layer 282, and the crystal grown layer283 formed in the window region in the masking layer 282. The hexagonalpyramids are arranged in a matrix. The crystal grown layer 283 (in theshape of a hexagonal pyramid) has the slant side faces as the S-plane.The hexagonal pyramid has the cross section as shown in FIG. 69. Theactive layer (which is not shown) is formed on the slant S-plane. Thelight generated by the device is reflected by the reflecting planeparallel to the S-plane, which improves light emergence efficiency.Therefore, the semiconductor light-emitting device has high brightnessand the slant crystal grown layer as the base of the reflecting plane isreadily formed by selective growth. Thus, the device effectivelyrelieves brightness saturation and improves device reliability.

Example 24

[0388] This example demonstrates a semiconductor light-emitting devicein which the crystal grown layer 293 on the substrate for growth 290takes the shape of a hexagonal prismoid, as shown in FIG. 81. The deviceincludes the substrate for growth 290, the underlying layer for growth291 formed thereon, the masking layer 292, and the crystal grown layer293 formed in the window region in the masking layer 292. The hexagonalprismoids are arranged in a matrix pattern. The crystal grown layer 293(in the shape of a hexagonal prismoid) has the slant side faces 293S asthe S-plane and the top face 293C as the C-plane which is identical withthe principal plane of the substrate. The base of the hexagonal prismoidis the M-plane or the (1-100) plane, which is formed low (i.e., near thebase of the hexagonal prismoid). The hexagonal prismoid has the crosssection as shown in FIG. 69. The active layer (which is not shown) isformed on the slant S-plane and the C-plane. The light generated by thedevice is reflected by the reflecting plane parallel to the S-plane,which improves light emergence efficiency. Therefore, the semiconductorlight-emitting device has high brightness and the slant crystal grownlayer as the base of the reflecting plane is readily formed by selectivegrowth. Thus, the device effectively relieves brightness saturation andimproves device reliability.

Example 25

[0389] This example demonstrates a semiconductor light-emitting devicein which the crystal grown layers 298 and 299 on the substrate forgrowth 295 take respectively the shape of a hexagonal pyramid and aquadrangular prismoid, as shown in FIG. 82. The device includes thesubstrate for growth 295, the underlying layer for growth 296 formedthereon, the masking layer 297, and the crystal grown layers 298 and 299formed in the window region in the masking layer 297. The crystal grownlayer 298 takes the shape of a hexagonal pyramid, and the crystal grownlayer 299 takes the shape of a quadrangular prismoid. The hexagonalpyramids and quadrangular prismoids are arranged in a matrix, and theyare arranged in line alternately.

[0390] The crystal grown layer 299 (in the shape of a quadrangularprismoid) has the slant side faces 299S as the S-plane, another slantfaces 229Z as the (11-22) plane, and the top face 299C as the C-planewhich is identical to the principal plane of the substrate. The crystalgrown layer 298 (in the shape of a hexagonal pyramid) has the slant sidefaces 298S as the S-plane. The hexagonal pyramid has the cross sectionas shown in FIG. 69. The active layer (which is not shown) is formed onthe slant S-plane and the C-plane. The light generated by the device isreflected by the reflecting plane parallel to the S-plane, whichimproves light emergence efficiency. Therefore, the semiconductorlight-emitting device has high brightness and the slant crystal grownlayer as the base of the reflecting plane is readily formed by selectivegrowth. Thus, the device effectively relieves brightness saturation andimproves device reliability.

Example 26

[0391] This example demonstrates a process for producing theabove-mentioned semiconductor light-emitting device. The process will bedescribed with reference to FIGS. 83 to 88.

[0392] First, on a substrate for growth 300 such as a sapphire substratethe n-type GaN layer 301 is formed by MOCVD or the like as an underlyinglayer for growth, as shown in FIG. 83. The n-type GaN layer 301 needsnot be n-type initially. However, it is acceptable so long as itsuppermost surface is n-type. The desired n-type GaN layer 301 may beformed by doping with silicon, for instance.

[0393] Then, on the entire surface of the n-type GaN layer 301 themasking layer 302 is formed by CVD as a growth inhibiting film, such asa silicon oxide film, a silicon nitride film, a tungsten film, and thelike. In the masking layer 302, the hexagonal window region 303, inwhich the device will be formed, is formed, as shown in FIG. 84.

[0394] Subsequently, selective growth is carried out such that then-type (Al)GaN layer 304 (as the crystal grown layer) is grown from thewindow region 303. This n-type (Al)GaN layer 304, which takes the shapeof an approximately hexagonal pyramid, functions also as a claddinglayer. The slant side face is the S-plane.

[0395] On the slant side face, the InGaN layer 305 (as an active layer)and the p-type (Al)GaN layer 306, are formed as shown in FIG. 86. TheInGaN layer 305 as an active layer extends broadly over the S-plane ofthe (Al)GaN layer 304 as the crystal grown layer, not parallel to theprincipal plane of the substrate for growth. The area S of the activelayer is larger than the area of the window region 303 and the projectedarea of the crystal grown layer, and is formed with sufficient expanse.It is possible to form an AlGaN cap layer on the InGaN layer 305. Theslant crystal face of the p-type (Al)GaN layer 306 functions as thereflecting plane.

[0396] Where poly-GaN is grown on the masking layer, unnecessary partsare removed by etching. The masking layer 302 is removed partly orentirely to form the n-side contact region 307, as shown in FIG. 87. Thep-electrode 309 of Ni/Pt/Au is formed by vapor deposition or the like.The n-electrode 308 of Ti/Al/Pt/Au is formed in the contact region 307by lift-off technique or the like (FIG. 88). After alloying, the deviceon the substrate is completed. Since the p-electrode 309 is formed onthe p-type (Al)GaN layer 306 which functions as a reflecting plane or areflecting region, it also functions as a reflecting film and alight-shielding film.

[0397] The individual devices are so small that it is difficult toseparate them from one another. However, it is only necessary toseparate them into groups by dicing, cleavage, or the like, each groupincluding devices arranged in one dimension or two dimensions.Individual devices in each group may or may not be driven independently.The GaN crystals grown on the sapphire substrate can be peeled off fromthe sapphire substrate if the sapphire/GaN interface is subjected to UVlaser abrasion through the sapphire, as reported by W. S. Wong et al. inAPL-75-10, 1360-2. If the first grown film (the first conductive film)is removed by etching before or after laser abrasion, it is possible toform a single semiconductor light-emitting device having the basicstructure according to an embodiment of the present invention.

[0398] As mentioned above, the process in this example offers anadvantage that the S-plane can be formed easily by selective growth andthe active layer can be formed on the crystal grown layer whose sideface is the S-plane. Thus, it is possible to form the reflecting planeby itself. The light generated by the device is partly reflected by thereflecting plane parallel to the slant crystal plane formed by selectivegrowth. This reflection improves light emergence efficiency and hence,the semiconductor light-emitting device has high brightness.

Example 27

[0399] This example demonstrates a semiconductor light-emitting devicehaving the structure as shown in FIG. 89. The device includes thesubstrate for growth 310, the second grown layer 311 formed partlythereon, the first conductive layer 311 (covering the second grown layer311), the active layer 313, and the second conductive layer 319.Although there is not a masking layer or window regions, the area of theactive layer 313 is larger than the projected area of the crystal grownlayer, thereby effectively relieving brightness saturation and improvingdevice reliability.

[0400] In other words, even if a growth inhibiting film (such as amasking layer) is not used, it is possible to form a stable surface andproduce the same effect as that which would be obtained by forming agrowth inhibiting film, if microfabrication is carried out by etching(for example, surface irregularities are formed on the substrate forgrowth or the crystal film which has been grown previously).

[0401] Additionally, according to an embodiment of the presentinvention, a hexagonal opening is most desirable as the window region inwhich the hexagonal pyramid is grown. However, the shape of the openingor the direction of the boundary of the opening is arbitrary because thestable plane is eventually formed by itself even with growth through around opening. The present invention is applicable also to the structurein which the stable plane, such as the (11-22) plane and the (1-100)plane other than the (1-101) plane in a wurtzite crystal, is formed byitself.

[0402] At present, red LEDs are usually made from an AlGaInP compound ofzincblende structure. This compound has stable planes such as the (011)plane and the (111) plane with respect to the (001) substrate. If it isgrown under adequate conditions, it is possible to form the stable planeand the active layer thereon.

[0403] The advantage of the semiconductor light-emitting device and itsproduction process according to an embodiment of the present inventionis that it is possible to increase the effective V/III ratio byutilizing the slant crystal plane slanting to the principal plane of thesubstrate. This permits more atoms constituting the compound crystal tobe taken up and decreases the fluctuation of light emission. Moreover,it is possible to suppress the dissociation of nitrogen atoms andimprove crystal properties, thereby decreasing the density of pointdefects. This prevents brightness from becoming saturated when thelight-emitting device is supplied with a strong current. The slantcrystal plane slanting to the principal plane of the substrate preventsmultiple reflection and hence, permits the generated light to emergeefficiently.

[0404] The selective growth to form the crystal layer as the slantcrystal plane (such as the S-plane) gives minute devices in a smallrange. Thus, it is possible to densely arrange the devices or toseparate the devices from one another by dicing or the like. Part of thestable plane resulting from selective growth is flat on the atomicscale; it has no fluctuation in brightness and it permits light emissionwith a narrow half width. Therefore, this plane can be applied tosemiconductor light-emitting diodes as well as semiconductor lasers.

[0405] The semiconductor light-emitting device according to anembodiment of the present invention is characterized in that part oflight emerging from it is one which has been reflected by the reflectingplane which is formed by selective growth parallel to the slant crystalplane. Reflection improves light emergence efficiency and hence, thesemiconductor light-emitting device has high brightness. The slantcrystal layer as the base of the reflecting plane is readily formed byselective growth without additional production steps such as etching.Moreover, the active layer parallel to the slant crystal plane has alarge effective area, which leads to reduced resistance, reduced heatgeneration, and improved reliability. With a large effective area, theactive layer has a reduced load per unit area, which contributes to highbrightness and high reliability. This produces its pronounced effect inthe case of miniaturized devices. The semiconductor light-emittingdevice of the present invention is characterized by the large areapossessed by the active layer, conductive layer, and electrode. Theslant crystal plane helps improve the light emergence efficiency.

[0406] One feature of the semiconductor light-emitting device and itsproduction process according to an embodiment of the present inventionis that the cladding layer of a first conductivity type, the activelayer, and the cladding layer of a second conductivity type partly orentirely extend to the masking layer around the opening. An advantage ofthis structure (with the masking layer remaining) is that the laterallygrown part is held by a support which does not disappear. Moreover, themasking layer relieves steps due to the selectively grown structure. Themasking layer, functioning as a supporting layer of the first grownlayer, also keeps the p-electrode and the n-electrode apart withcertainty, thereby preventing short-circuiting, even when the substrateis stripped off by laser irradiation.

[0407] The semiconductor light-emitting device of the present inventionmay be constructed such that the cladding layer of a first conductivitytype, the active layer, and the cladding layer of a second conductivitytype entirely cover the second grown layer and the ends of the claddinglayer of a first conductivity type, the active layer, and the claddinglayer of a second conductivity type come into direct contact with themasking layer. This structure protects the active layer from oxidationand other deterioration and also produces an effect of increasing thelight emission area.

[0408] An advantage of the semiconductor light-emitting device accordingto an embodiment of the present invention is that the selective growthto form the crystal layer as the slant crystal plane gives minutedevices in a small range. Thus it is possible to densely arrange thedevices or to separate the devices from one another by dicing or thelike. Part of the stable plane resulting from selective growth is flaton the atomic scale; it has no fluctuation in brightness and it permitslight emission with a narrow half width. Therefore, this plane can beapplied to semiconductor light-emitting diodes as well as semiconductorlasers.

[0409] Another advantage of the semiconductor light-emitting device ofthe present invention is that the active layer has a large effectivearea, which leads to reduced resistance, reduced heat generation, andimproved reliability. With a large effective area, the active layer hasa reduced load per unit area, which contributes to high brightness andhigh reliability. This produces its pronounced effect in the case ofminiaturized devices. The semiconductor light-emitting device of thepresent invention is characterized by the large area possessed by theactive layer, conductive layer, and electrode. The slant crystal planehelps improve the light emergence efficiency.

[0410] Although the present invention has been described with referenceto specific embodiments, those of skill in the art will recognize thatchanges may be made thereto without departing from the spirit and scopeof the invention as set forth in the hereafter appended claims.

1. A semiconductor light-emitting device comprising: a substrateincluding a substrate surface positioned along a substrate surfaceplane; a crystal layer including a crystal surface oriented along acrystal surface plane diagonally intersecting the substrate surfaceplane; and a first conductive layer, an active layer, and a secondconductive layer each formed along at least a portion of the crystalsurface.
 2. The semiconductor light-emitting device as claimed in claim1, wherein the crystal layer comprises a wurtzite crystal structure. 3.The semiconductor light-emitting device as claimed in claim 1, whereinthe crystal layer is composed of a nitride semiconductor material. 4.The semiconductor light-emitting device as claimed in claim 1, whereinthe crystal layer is formed by selective growth on the substrate with amaterial layer capable of growth interposed therebetween.
 5. Thesemiconductor light-emitting device as claimed in claim 4, wherein thematerial layer capable of growth is selectively removed during selectivegrowth to form the crystal layer.
 6. The semiconductor light-emittingdevice as claimed in claim 4, wherein the semiconductor light-emittingdevice farther comprises a masking layer having an opening through whichthe crystal layer is selectively grown.
 7. The semiconductorlight-emitting device as claimed in claim 6, wherein the crystal layeris formed by selective growth such that the crystal layer extendslaterally from the opening in the masking layer.
 8. The semiconductorlight-emitting device as claimed in claim 1, wherein the substrate planecomprises a C-plane.
 9. The semiconductor light-emitting device asclaimed in claim 1, wherein the crystal surface plane comprises at leastone of a S-plane and a (11-22) plane.
 10. The semiconductorlight-emitting device as claimed in claim 1, wherein the crystal surfaceplane comprises a plane having a plane orientation inclined at an angleranging from about 5 to about 6 degrees with respect to at least one ofa S-plane and a (11-22) plane.
 11. The semiconductor light-emittingdevice as claimed in claim 1, wherein a current is injected into theactive layer.
 12. The semiconductor light-emitting device as claimed inclaim 1, wherein the active layer comprises InGaN.
 13. The semiconductorlight-emitting device as claimed in claim 1, wherein the crystal layercomprises a substantially symmetrical hexagonal structure.
 14. Thesemiconductor light-emitting device as claimed in claim 1, wherein aportion of the crystal surface is oriented along a C-plane andpositioned centrally along the crystal structure with respect to asecond portion of the crystal surface that is oriented along the crystalsurface plane which diagonally intersects the substrate surface plane.15. An image display unit comprising: a plurality of semiconductorlight-emitting devices arranged so as to emit light in response to asignal, each of the semiconductor light-emitting devices comprising asubstrate including a substrate surface positioned along a substratesurface plane, a crystal layer including a crystal surface orientedalong a crystal surface plane diagonally intersecting the substratesurface plane, and a first conductive layer, an active layer, and asecond conductive layer each formed along at least a portion of thecrystal surface.
 16. A lighting system comprising: a plurality ofsemiconductor light-emitting devices, each of the semiconductorlight-emitting devices comprising a substrate including a substratesurface positioned along a substrate surface plane, a crystal layerincluding a crystal surface oriented along a crystal surface planediagonally intersecting the substrate surface plane, and a firstconductive layer, an active layer, and a second conductive layer eachformed along at least a portion of the crystal surface.
 17. The lightingsystem as claimed in claim 16, wherein each of the semiconductorlight-emitting devices are arranged so as to emit light in response toan identical signal.
 18. A process for producing a semiconductorlight-emitting device, the process comprising the steps of: providing asubstrate including a substrate surface oriented along a substratesurface plane; forming a crystal seed layer on the substrate surface;forming a masking layer on the crystal seed layer, wherein the maskinglayer includes an opening; forming a crystal layer by selective growthof the crystal seed layer through the opening of the masking layer,wherein the crystal layer includes a crystal layer surface orientedalong a crystal layer plane that diagonally intersects the substratesurface; and forming each of a first conductive layer, an active layer,and a second conductive layer along at least a portion of the crystallayer surface.
 19. The process as claimed in claim 18, wherein thesubstrate surface plane comprises a C-plane.
 20. The process as claimedin claim 18, further comprising the step of forming a plurality ofsemiconductor light-emitting devices spaced apart along the substrate.21. The process as claimed in claim 20, further comprising the step offorming an electrode on at least a side of each semiconductorlight-emitting device.
 22. A semiconductor light-emitting devicecomprising: a substrate including a substrate surface positioned along asubstrate surface plane; a crystal layer including a crystal layersurface oriented along a crystal surface plane defined as a S-planewhich diagonally intersects the substrate surface plane; and a layer ofa first conductivity type, an active layer, and a layer of a secondconductivity type each formed along the S-plane.
 23. The semiconductorlight-emitting device as claimed in claim 22, wherein the crystal layercomprises a wurtzite crystal structure.
 24. The semiconductorlight-emitting device as claimed in claim 22, wherein the crystal layeris composed of a nitride semiconductor material.
 25. The semiconductorlight-emitting device as claimed in claim 22, wherein the crystal layeris formed by selective growth on the substrate with a material layercapable of growth interposed therebetween.
 26. The semiconductorlight-emitting device as claimed in claim 25, wherein the material layercapable of growth is selectively removed during selective growth to formthe crystal layer.
 27. The semiconductor light-emitting device asclaimed in claim 25, wherein the semiconductor light-emitting devicefurther comprises a masking layer having an opening through which thecrystal layer is selectively grown.
 28. The semiconductor light-emittingdevice as claimed in claim 27, wherein the crystal layer is formed byselective growth such that the crystal layer extends laterally from theopening in the masking layer.
 29. The semiconductor light-emittingdevice as claimed in claim 22, wherein the substrate surface planecomprises a C+ plane.
 30. The semiconductor light-emitting device asclaimed in claim 22, wherein a current is injected into the activelayer.
 31. A semiconductor light-emitting device comprising: a substrateincluding a substrate surface positioned along a substrate surfaceplane; a crystal layer comprising an approximately hexagonal pyramid,having a face oriented along an S-plane that diagonally intersects thesubstrate surface plane; and a layer of a first conductivity type, anactive layer, and a layer of a second conductivity type each formedalong at least a portion of the approximately hexagonal pyramid.
 32. Thesemiconductor light-emitting device as claimed in claim 31, wherein acurrent is injected into the active layer such that a current density islower near or at an apex of the approximately hexagonal pyramid than inthe face of the approximately hexagonal pyramid.
 33. A semiconductorlight-emitting device comprising: a substrate including a substratesurface positioned along a substrate surface plane; a crystal layercomprising an approximately hexagonal prismoid, having a face orientedabout an S-plane, and a top region oriented about a C-plane; and a layerof a first conductivity type, an active layer, and a layer of a secondconductivity type each formed along at least a portion of theapproximately hexagonal prismoid.
 34. An image display unit comprising:a plurality of semiconductor light-emitting devices arranged so as toemit light in response to a signal, each of the semiconductorlight-emitting devices comprising a substrate including a substratesurface positioned along a substrate surface plane, a crystal layerincluding a crystal surface oriented along a crystal surface planedefined as a S-plane which diagonally intersects the substrate surfaceplane, and a first conductive layer, an active layer, and a secondconductive layer each formed along at least a portion of the crystalsurface.
 35. A lighting system comprising: a plurality of semiconductorlight-emitting devices, each of the semiconductor light-emitting devicescomprising a substrate including a substrate surface positioned along asubstrate surface plane, a crystal layer including a crystal surfaceoriented along a crystal surface plane defined as a S-plane whichdiagonally intersects the substrate surface plane, and a firstconductive layer, an active layer, and a second conductive layer eachformed along at least a portion of the crystal surface.
 36. The lightingsystem as claimed in claim 35, wherein each of the semiconductorlight-emitting devices are arranged so as to emit light in response toan identical signal.
 37. A process for producing a semiconductorlight-emitting device, the process comprising the steps: providing asubstrate including a substrate surface oriented along a substratesurface plane; forming a masking layer on the substrate, wherein themasking layer includes an opening; forming a crystal layer by selectivegrowth through the opening of the masking layer, wherein the crystallayer includes a crystal layer surface oriented along a crystal layerplane defined as a S-plane which diagonally intersects the substratesurface plane; and forming each of a first conductive layer, an activelayer, and a second conductive layer along at least a portion of thecrystal layer surface.
 38. The process for producing a semiconductorlight-emitting device as claimed in claim 37, wherein the substratesurface plane comprises a C+ plane.
 39. The process for producing asemiconductor light-emitting device as claimed in claim 37, furthercomprising the steps of: forming a plurality of the semiconductorlight-emitting devices on the substrate; and separating the plurality ofsemiconductor light-emitting devices.
 40. The process for producing asemiconductor light-emitting device as claimed in claim 39, wherein eachseparated semiconductor light-emitting device comprises at least oneelectrode formed on a side.
 41. A semiconductor light-emitting devicecomprising: a substrate including a substrate surface positioned along asubstrate surface plane; a crystal grown layer formed by selectivegrowth and including a crystal surface oriented along a crystal surfaceplane diagonally intersecting the substrate surface plane; an activelayer which is formed along at least a portion of the crystal grownlayer that emits light upon injection of an amount of current; and areflecting region which is formed substantially parallel to the crystalsurface plane and reflects at least a portion of the light emerging fromthe active layer.
 42. The semiconductor light-emitting device as claimedin claim 41, wherein the active layer is formed from a compoundsemiconductor having a wurtzite crystal structure.
 43. The semiconductorlight-emitting device as claimed in claim 41, wherein the active layeris approximately parallel to the crystal surface plane.
 44. Thesemiconductor light-emitting device as claimed in claim 41, wherein theactive layer is approximately parallel to a S-plane.
 45. Thesemiconductor light-emitting device as claimed in claim 41, wherein theactive layer is approximately parallel to a plane having a planeorientation inclined at an angle ranging from about 5 to about 6 degreeswith respect to at least one a S-plane and a (11-22) plane.
 46. Thesemiconductor light-emitting device as claimed in claim 41, wherein thereflecting region comprises at least two reflecting planes thatintersect at an angle less than 180°.
 47. The semiconductorlight-emitting device as claimed in claim 41, wherein the active layeris formed from a nitride compound semiconductor.
 48. The semiconductorlight-emitting device as claimed in claim 47, wherein the active layeris formed from a gallium nitride compound semiconductor.
 49. Thesemiconductor light-emitting device as claimed in claim 41, wherein theactive layer contains In.
 50. The semiconductor light-emitting device asclaimed in claim 41, wherein the active layer is separated for eachdevice.
 51. The semiconductor light-emitting device as claimed in claim41, further comprising an underlying layer formed on the substrate,wherein the selective growth of the crystal grown layer is derived fromthe underlying layer.
 52. A process for producing a semiconductorlight-emitting device, the process comprising the steps of: providing asubstrate including a substrate surface oriented along a substratesurface plane; selectively growing a crystal layer including a crystalsurface oriented along a crystal surface plane diagonally intersectingthe substrate surface plane; forming an active layer approximatelyparallel to the crystal surface plane; and forming a reflecting regionsubstantially parallel to the crystal surface plane.
 53. A semiconductorlight-emitting device comprising: a substrate including a substratesurface oriented along a substrate surface plane; a first grown layerincluding a first grown layer conductivity type formed on the substrate;a masking layer formed on the first grown layer; a second grown layer ofa second grown layer conductivity type formed by selective growththrough an opening in the masking layer and including a crystal surfaceoriented along a crystal surface plane; a first cladding layer includinga first cladding layer conductivity type formed along at least a portionof the crystal surface plane; an active layer; and a second claddinglayer including a second cladding layer conductivity type, wherein atleast one of the first cladding layer, the active layer, and the secondcladding layer cover the masking layer surrounding the opening.
 54. Thesemiconductor light-emitting device as claimed in claim 53, wherein thefirst grown layer conductivity type, the second grown layer conductivitytype, and the first cladding layer conductivity type comprise a firstconductivity type and the second cladding layer conductivity typecomprises a second conductivity type.
 55. The semiconductorlight-emitting device as claimed in claim 53, wherein the crystalsurface plane of the second grown layer diagonally intersects thesubstrate surface plane.
 56. The semiconductor light-emitting device asclaimed in claim 53, wherein the first and second grown layers comprisea wurtzite crystal structure.
 57. The semiconductor light-emittingdevice as claimed in claim 53, wherein the second grown layer iscomposed of a nitride semiconductor.
 58. The semiconductorlight-emitting device as claimed in claim 53, wherein the substratesurface plane is a C-plane.
 59. A semiconductor light-emitting devicecomprising: a substrate; a first grown layer including a first grownlayer conductivity type formed on the substrate; a masking layer formedon the first grown layer; a second grown layer including a second grownlayer conductivity type formed by selective growth through an opening inthe masking layer and including a crystal surface oriented along acrystal surface plane; a first cladding layer including a first claddinglayer conductivity type formed along at least a portion of the crystalsurface plane; an active layer; and a second cladding layer including asecond cladding layer conductivity type, wherein the first claddinglayer, the active layer, and the second cladding layer are formed as tosubstantially cover the second grown layer.
 60. The semiconductorlight-emitting device as claimed in claim 59, wherein the first grownlayer conductivity type, the second grown layer conductivity type, andthe first cladding layer conductivity type comprise a first conductivitytype and the second cladding layer conductivity type comprises a secondconductivity type.
 61. A semiconductor light-emitting device comprising:a substrate; a first grown layer of a first grown layer conductivitytype formed on the substrate; a masking layer formed on the first grownlayer; a second grown layer of a second grown layer conductivity typeformed by selective growth through an opening in the masking layer andincluding a crystal surface oriented along a crystal surface plane; afirst cladding layer of a first cladding layer conductivity type formedalong at least a portion of the crystal surface plane; an active layer;and a second cladding layer of a second cladding layer conductivitytype, wherein the first cladding layer, the active layer, and the secondcladding layer are formed substantially parallel to the crystal surfaceplane such that an end region of at least one of the first claddinglayer, the active layer, and the second cladding layer contacts themasking layer.
 62. The semiconductor light-emitting device as claimed inclaim 61, wherein the first grown layer conductivity type, the secondgrown layer conductivity type, and the first cladding layer conductivitytype comprise a first conductivity type and the second cladding layerconductivity type comprises a second conductivity type.
 63. An imagedisplay unit comprising: a plurality of semiconductor light-emittingdevices arranged so as to emit light in response to a signal, each ofthe semiconductor light-emitting devices comprising a substrate, a firstgrown layer of a first conductivity type formed on the substrate, amasking layer formed on the first grown layer, a second grown layer ofthe first conductivity type formed by selective growth through anopening in the masking layer and including a crystal surface orientedalong a crystal surface plane, a first cladding layer of the firstconductivity type formed along at least a portion of the crystal surfaceplane, an active layer, and a second cladding layer of a secondconductivity type, wherein the first cladding layer, the active layer,and the second cladding layer are formed substantially parallel to thecrystal surface plane such that an end region of at least one of thefirst cladding layer, the active layer, and the second cladding layerextends to the masking layer in proximity to the opening.
 64. A lightingsystem comprising: a plurality of semiconductor light-emitting devices,each of the semiconductor light-emitting devices comprising a substrate,a first grown layer including a first conductivity type formed on thesubstrate, a masking layer formed on the first grown layer, a secondgrown layer including the first conductivity type formed by selectivegrowth through an opening in the masking layer and including a crystalsurface oriented along a crystal surface plane, a first cladding layerincluding the first conductivity type formed along at least a portion ofthe crystal surface plane, an active layer, and a second cladding layerof a second conductivity type, wherein the first cladding layer, theactive layer, and the second cladding layer are formed substantiallyparallel to the crystal surface plane such that an end region of atleast one of the first cladding layer, the active layer, and the secondcladding layer extends to the masking layer in proximity to the opening.65. The lighting system as claimed in claim 64, wherein each of thesemiconductor light-emitting devices are arranged so as to emit light inresponse to an identical signal.
 66. A process for producing asemiconductor light-emitting device, the process comprising the stepsof: providing a substrate including a substrate surface oriented along asubstrate surface plane; forming a first grown layer on the substrate;forming a masking layer having an opening on the first grown layer;selectively growing a second grown layer through the opening in themasking layer, wherein the second grown layer includes a crystal surfaceoriented along a crystal surface plane; and forming a cladding layer ofa first conductivity type, an active layer, and a cladding layer of asecond conductivity type each substantially parallel to the crystalsurface plane extending to the masking layer in proximity of theopening.
 67. The process for producing a semiconductor light-emittingdevice as claimed in claim 66, wherein the crystal surface plane of thesecond grown layer diagonally intersects the substrate surface plane.68. A semiconductor light-emitting device comprising: a substrateincluding a substrate surface oriented along a substrate surface plane;and an active layer formed along at least a portion of a selectivelygrown crystal layer via a window region along the substrate surfaceplane such as to be disposed between a first conductive layer and asecond conductive layer and oriented along an active layer plane that isnot parallel to the substrate surface plane, and wherein an area of theactive layer is larger than at least one of an area of the window regionand a projected area of the crystal layer derived from projecting thecrystal layer to the substrate surface plane in a normal direction. 69.The semiconductor light-emitting device as claimed in claim 68, whereinthe active layer comprises a compound semiconductor having a wurtzitecrystal structure.
 70. The semiconductor light-emitting device asclaimed in claim 69, wherein the active layer is substantially parallelto a S-plane.
 71. The semiconductor light-emitting device as claimed inclaim 70, wherein the active layer is formed such that it extendslaterally from the window region.
 72. The semiconductor light-emittingdevice as claimed in claim 68, further comprising: a first electrodeconnected to the first conductive layer; and a second electrodeconnected to the second conductive layer, wherein the first electrodeand second electrode are capable of injecting current into the activelayer.
 73. The semiconductor light-emitting device as claimed in claim68, wherein the active layer comprises a nitride compound semiconductor.74. The semiconductor light-emitting device as claimed in claim 73,wherein the active layer comprises a gallium nitride compoundsemiconductor.
 75. The semiconductor light-emitting device as claimed inclaim 68, wherein the active layer comprises In.
 76. The semiconductorlight-emitting device as claimed in claim 68, further comprising aplurality of semiconductor light-emitting devices selectively grown suchthat the active layer of each semiconductor light-emitting device isseparated from the active layer of adjacent semiconductor light-emittingdevices.
 77. A semiconductor light-emitting device as claimed in claim68, wherein the selective growth is derived from an underlying layerformed on the substrate.
 78. A semiconductor light-emitting devicecomprising a substrate including a substrate surface oriented along asubstrate surface plane; and an active layer formed by selective growthsuch as to be disposed between a first conductive layer and a secondconductive layer and oriented along an active layer plane that is notparallel to the substrate surface plane, and wherein a portion of theactive layer is directed away from the active layer plane towards thesubstrate.
 79. A semiconductor light-emitting device comprising: asubstrate including a substrate surface oriented along a substratesurface plane; and an active layer formed along at least a portion of aselectively grown crystal layer such as to be disposed between a firstconductive layer and a second conductive layer and oriented along anactive layer plane that is not parallel to the substrate surface plane,and wherein an area of the active layer greater than or equal to a sumof a projected area of the crystal layer derived from projecting thecrystal layer to the substrate in a normal direction and an area inwhich at least one of the conductive layers contacts a respectiveelectrode formed on the substrate.
 80. A process for producing asemiconductor light-emitting device, the process comprising the stepsof: forming an underlying layer on a substrate; forming a masking layerhaving a window region on the underlying layer; selectively growing acrystal grown layer through the window region; and forming a firstconductive layer, an active layer, and a second conductive layer on asurface of the crystal grown layer, wherein the active layer includes acrystal surface with a surface area larger than a projected area derivedfrom projecting the crystal surface toward the substrate in a normaldirection.
 81. A process for producing a semiconductor light-emittingdevice, the process comprising the steps of: providing a first substrateincluding a first substrate surface oriented along a first substratesurface plane; forming a crystal seed layer on the first substratesurface; forming a masking layer on the crystal seed layer, wherein themasking layer includes an opening; forming a crystal layer by selectivegrowth of the crystal seed layer through the opening of the maskinglayer, wherein the crystal layer includes a crystal layer surfaceoriented along a crystal layer plane that diagonally intersects thefirst substrate surface plane; forming each of a first conductive layer,an active layer, and a second conductive layer along at least a portionof the crystal layer surface; embedding each of the first conductivelayer, the active layer and the second conductive layer and the secondconductive layer in a resin material layer formed on a second substrate;removing the second substrate by laser abrasion; separating the crystalseed layer and masking layer from a substrate region of the substrate;and forming an electrode on at least a portion of the substrate region.82. The method as claimed in 81, wherein the crystal seed layer and themasking layer are separated by peeling off.